Abstract: Although China's farmland reform adopted the top-down approach, it could not succeed without the support from farmers. The construction of farmland legal system is also no exception. Compared with the law of the state, farmland conventional law originated naturally in the countryside with distinct features of naturality, regionality and human nature. Due to the limited regulatory scope and functions of the law of the state, it is impossible to formulate specific regulations concerning each aspect of farmland. Farmland conventional law makes up for the deficiency and maintains the social order in rural area, whose practical rationality cannot be ignored. Additionally, farmland conventional law is significant to the construction of farmland legal system, providing it with the basic content, supplement in the implementation process and reference for procedure. Thus, in the course of farmland reform, farmland conventional law should be valued; its interaction and integration with the law of the state should be realized.