In this paper, chitosan was treated by diatomite, and then granulated by gel method, after crosslinking with epichlorohydrin and amination with diethylenetriamine, molybdate was immobilized on chitosan particles to prepare catalyst particles that had many characteristics, such as acid resistance, high mech. strength and strong adsorption capacity.In the application experiments of preparing mannose from glucose by epimerizationm, the conversion rate of glucose was above 30%, and the effective repeated use rate was above 10 times.