AIM:To study efficacy and security of triamcinolone acetonide for the prevention of capsule opacification after cataract surgery of diabetic. METHODS:Totally 173 diabetic patients 296 eyes who received phaco +IOL in our hospital from March 2007 to September 2011 were randomly divided into three groups. Group A (102 eyes) received balanced salt solution, and group B (93 eyes) diluted triamcinolone acetonide liquid the water separator, C group (101 eyes) using a diluted triamcinolone acetonide water separation joint anterior chamber irrigation. After 1 week; 1, 3, 6, 12 months,the best-corrected visual acuity(BCVA), posterior capsule opacification (PCO) grading situation observed in patients. RESULTS:One week postoperatively, the difference between BCVA in group A and group B, C was statistically significant (P<0.05). The rest of time points, there was no significant difference betweengroups A, B and C(P>0.05). After surgery, PCO grading in group A had statistically significant difference compared with that in group B, C(P<0.01), PCO grading in group B and group C was lower than that in group A and PCO grading in group C was lower than that in group B (P<0.05 ).CONCLUSION:Water separation and anterior chamber wash of triamcinolone acetonide can effectively reduce the incidence rate of PCO after diabetic cataract surgery. 