With the analysis of the structure of gypsum crystal,the structure of vegetal fiber,the microstructure of vegetal fiberboard based on gypsum and its material characteristic,the theory of sobbing water of vegetal fiberboard based on gypsum and relevant measure of waterproof are approached.The domestic and overseas research works of waterproof performance of vegetal fiber and gypsum board are introduced.The features of waterproof of vegetal fiberboard based on gypsum are described.