Nanjing County in Fujian has more than 15,000 earth buildings of various types, including more than 1,300 large-scale square earth buildings, which can be called the "Earth Building Kingdom". It brings together the highest, largest, smallest, strangest, oldest and most spectacular earth buildings. Among them, Tianluokeng Earth Building Group, Hekeng Earth Building Group, Huaiyuan Building, Hegui Building, etc. are the models of earth building architecture. Thousands of earth buildings are like "flying saucers falling from the sky" and "mushrooms growing on the ground", dotted on the beautiful land of Nanjing, forming a wonderful landscape, known as "the world's unique mythical mountain village architectural model". The site selection and construction of Hua'an Earth Building are based on the principles of family prosperity and safety, and are laid out in accordance with the traditional Chinese Feng Shui concept. Its architectural design and plane layout are very scientific, reasonable, practical and systematic, and are full of modern home concepts. Among them, Eryi Building in Dadi Village, Xiandu Town is the most outstanding representative. It is the earliest building listed as a national key cultural relic protection unit among Fujian Earth Buildings and a world-class residential architectural treasure. The construction technique of earthen buildings cleverly uses the terrain of the mountainous area and local raw soil, wood, rocks and other building materials. It is very economical, extremely strong, defensive and beautiful. While inheriting and innovating the traditional raw soil construction technology, Fujian earthen buildings also inherit the essence of Chinese traditional culture and are a witness to the cultural tradition of living together in clans. The earthen buildings are built with ancient rammed earth wall board building tools, and the tools mainly include plywood, pestle and shovel, large and small clappers and other auxiliary tools. Rammed earth walls have strict rules from soil selection, proportion mixing, pile soil treatment, dryness and humidity control to ramming procedures and wall repairs. Carpenters design and process beams. In particular, the rooms of the round building are basically divided into equal parts according to the circumference (in the shape of a bucket), and carpenters create corresponding beams according to the situation, which is highly technical. The ancient rammed earth wall technology is the technical crystallization of the Central Plains rammed earth board construction technology after thousands of years of accumulation and improvement. It is the highest achievement of rammed earth civilization and can be called a unique building. However, with the development of society, the replacement of modern architectural models and modern materials has caused the ancient construction techniques of earthen buildings to be on the verge of being lost. This ancient technique, which has important historical significance and modern research value, urgently needs to be inherited and protected.