Abstract: Objective:To study the effect of the different particle size cellulose on intestine health in ovariectomized rats.Methods:40 female SD rats were randomly divided into five groups, which a group of rat ovarian pseudo resection, the rest of 4 groups of rats were ovariectomized surgery, a week wound healing after surgery, the ovarian with pseudo resection group and a group of ovariectomized group fed with basic feed, remaining three groups ovariectomized group added the mass fraction 10% of the ordinary cellulose ultrafine cellulose and nanocrystalline cellulose into basic feed.All rats were sacrificed after 28 days of feeding to assay body weight gain, cecal tissue weight, the amount of free ammonia, short-chain fatty acids (SCFAs) and microbe in cecum contents.Results:Fed these three kinds of particle size of the cellulose compared to the blank group, their cecal contents increased fecal excretion increased bacteria increased in the cecal contents, reduce harmful bacteria, the pH value decreases, the SCFAs were elevated and reduce the free ammonia.Conclusion:Rats fed three different granularity cellulose could increased the amount of defecation and promote rat intestinal fermentation, and the more refinement cellulose could increase rat intestinal fermentation, and could improve the intestinal health effectively.