The basal diet was formulated using vitamin B6-free casein as the protein source. Eight graded levels (0, 10, 30, 60,100,150,200 and 400 mg vitamin B6 per kg diet) of vitamin B6 were added to the basal diet. Each diet was fed to three replicate groups of E.sinensis (2.12±0.56) g for 10 weeks. Results showed that there were no significant differences in survival, weight gain, and the content of water and ash among crabs fed different diets. But protein utilization ratio (PUR) increased significantly with the increase of dietary vitamin B6. The highest PUR was found in crabs fed diet with 100 mg vitamin B6 per kg diet. Patterns of the content of crude protein and crude fat were similar to that of PUR. Crabs fed 100 mg vitamin B6/kg diet had a significantly higher protein and fat content than that fed 0 and 400 mg vitamin B6 per kg diet. Besides, different dietary vitamin B6 content also had significant effect on the activities of hepatopancreas glutamate pyruvate transaminase (ALT) ,while no significant difference was observed in glutamate aspartate transaminase (AST). But they both increased with the increase of dietary vitamin B6. The maximum hepatopancreas ALT activitiy was observed in crab fed the 100 mg vitamin B6 per kg diet, and was significantly higher than all the other, except 30 mg vitamin B6 per kg diet groups. Combined, results in this study indicated that through stimulating the activity of transaminase, vitamin B6 could assist the anabolism of protein, and then improved the accumulation of body protein and fat in crabs. Broken-line regression analysis showed that the optimum dietary pyridoxine requirement for maximum PUR and hepatopancreas ALT activity of E. sinensis under these experimental conditions was 81.675-85.74 mg pyridoxine per kg diet.