Abstract: Microcrystalline cellulose was prepared through extraction of cellulose from coconut mesocarp by nitric acid- ethanol method and then hydrolysis of the cellulose. The content of the cellulose was determined by spectrophotometry and the yield of the microcrystalline cellulose was obtained by titration. The result of single-factor experiment showed that optimized conditions for the extraction of cellulose from coconut mesocarp were as following: refluxing in water bath at 80℃,solid- liquid ratio of 1 ∶ 20( g / m L) and acid- glycol ratio of 1 ∶ 3 afford75.24μg / m L of cellulose by content.The optimized conditions for the preparation of microcrystalline cellulose from the resulted cellulose were described as follows: 100℃ as hydrolysis temperature,70 min as hydrolysis time,7% as HCl concentration and 1∶15( g / m L) as the solid- liquid ratio,microcrystalline cellulose was obtained in a yield of 97.50%. The microcrystalline cellulose prepared is characterized by IR. The process described in this paper gives great support for the utilization of coconut mesocarp.