Mazu Festival (Haikou Tianhou Worship), a traditional folk custom in Haikou City, Hainan Province, is one of the national intangible cultural heritages. Haikou Tianhou Worship began to take shape among the people in the Yuan Dynasty. It is a folk belief activity that worships and praises Mazu, with palaces (temples) as the main venues, and customs and temple fairs as the forms of expression. As the sea patron saint of the people in coastal areas, Mazu has been awarded 36 times by emperors of successive dynasties, with titles ranging from "Madam", "Heavenly Concubine", "Heavenly Queen" to "Heavenly Holy Mother", etc. The Hainanese people are accustomed to calling Mazu the Holy Mother of the Queen of Heaven, the Holy Mother of the Concubine of Heaven, and the Goddess of the Concubine of Heaven. According to the records of Hainan history books and local chronicles of successive dynasties, there were 5 Mazu temples built on Hainan Island in the Yuan Dynasty. By the Ming and Qing Dynasties, Mazu temples were spread across 13 counties and prefectures in Qiongzhou. In Hainan, there are Mazu temples in coastal areas as long as there are ports, docks and commercial ports. From the records of the construction and reconstruction of Mazu temples in the Ming and Qing dynasties, it is found that there were many government officials and businessmen who participated in the construction of Mazu temples at that time. Most of them were local county magistrates, county magistrates and foreign businessmen. It can be seen that the belief in Mazu was already prevalent in Hainan at that time. The belief in Mazu has been circulated among the people of Hainan since the Yuan Dynasty, and it has a history of nearly 800 years. On the birthday of Mazu (March 23 of the lunar calendar) and the anniversary of her death (September 9 of the lunar calendar), Hainan's Tianhou Palace (Tianfei Palace) will hold sacrificial activities. People created a god who is both a god and a human in the image of their mother, and put the great love of their mother on Mazu. The worship of Tianhou, which has been continued since the Yuan Dynasty, reflects the Hainan people's admiration for Mazu and their yearning and pursuit for a better life. The worship ceremony of Tianhou is divided into two types: family worship and temple worship. Among the three Mazu temples currently under key protection in Haikou, only the Haikou Tianfei Palace in Xinhai Village is close to the sea, so that the worship ceremony here can retain the link of worshiping the sea. Temple sacrifices are divided into daily sacrifices and temple fair sacrifices. During temple fair sacrifices, a sacrificial ceremony is held. The two most grand and solemn temple fair sacrifices each year are Mazu's birthday (March 23 of the lunar calendar) and ascension day (September 9 of the lunar calendar), which often attract thousands of believers to participate. The rituals and customs of worshipping the Queen of Heaven have been inherited and developed, and now have formed relatively fixed procedures and contents in Haikou. During the sacrifice, a sacrificial feast is set up on the platform in front of the palace (temple), and candlesticks and incense burners are placed. Sacrificial offerings including whole pigs (whole roasted pigs), sheep, chickens, seafood, rice and fruits are placed. The main priest reads the prayer, and the believers devoutly burn incense, worship and pray for blessings. Before and after the worship ceremony, there will be performance teams composed of art groups such as the honor guard, martial arts team, waist drum team, song and dance team, dragon dance team, lion dance team, etc., performing dragon and lion dances to the sound of music accompanied by local tunes, and the "Land Goddess" and "Land Goddess" will follow them in front, behind, and on the left and right with yangko dance steps. The most spectacular scene in the ceremony is the Mazu parade: four people carry the statue of Mazu out of the palace (temple) with a "luanjia", followed by the honor guard holding the general flag, the command flag, the first card, the knife stick, the "Heavenly Holy Mother" card, etc., and surrounded by a large group of believers, they parade along the predetermined route to the seaside and the streets. The Luanjia that Mazu sits on is not carried steadily, but swaying. It is said that the more it swings, the safer it will be. The boats that have been docked at the shore are lined up, and the boats are hung and filled with colorful flags. Wherever the parade team goes, firecrackers are set off. After the parade, the worshippers returned to the palace (temple) and saluted Mazu again, and the ceremony ended. As a folk activity of Mazu belief, Haikou Tianhou worship has a distinct regional color. Its heavy and rich ancient style and solemn atmosphere have formed a unique sacrificial culture. After historical accumulation, it has now become a representative traditional folk custom in Haikou. In 2014, the Mazu Festival (Haikou Tianhou Worship) applied by Haikou City, Hainan Province was approved by the State Council of the People's Republic of China and included in the fourth batch of national intangible cultural heritage list, project number: -36.