The leather paper making technique spread in Longyou, Zhejiang, has a history of more than 1,400 years. The Longyou County Chronicles of the Wanli Period of the Ming Dynasty has the reputation of "burning more paper, and the paper is better than other counties". Longyou leather paper uses mountain ash bark, wild cotton bark, and celtis bark as the main raw materials, and there are two processes and more than 30 processes in its production. The first is the leather material production process, which mainly includes cutting strips, steaming materials, peeling, steaming skin, stepping and washing, spreading and drying, making leather blanks, tearing and selecting, steaming, kneading and washing, squeezing, spreading and drying, washing, beating materials, selecting skins, washing, drying, and bagging materials; the second is the finished product production process, which includes squeezing materials, leather material troughing, troughing, adding juice, stirring, scooping paper, squeezing paper, baking paper, checking paper, cutting paper, and packaging. More than 50 tools with different functions are needed in the production, such as mountain knives, skin scraping knives, guillotines, steamers, paper curtains, curtain beds, and trough angles. The production process of Longyou leather paper depends entirely on the naked eye observation and hand experience of craftsmen. For example, the depth of the curtain bed in the pool and the size of the waves in the paper scooping process can only be operated by sight and touch, which determines the quality of the finished paper. With the leather paper making technique, more than 30 varieties of paper can be processed, such as painting paper, note paper, national color paper, special paper, etc., which are not only used for calligraphy and painting, but also for binding and packaging. The folk workshops in the southern mountainous area of Longyou County still preserve the complete handmade mountain yam leather paper and wild cotton leather paper craft. A few inheritors such as Wan Aizhu still guard this ancient handmade craft, but the scale is small and urgently needs protection.