Abstract: Objective: To observe the role of bilviscoelastic materials(dispersive and cohesive) in protection of corneal endothelium in cataract endocapsular phacoemulcification.Methods: Two types of cataracts were divided into 4 groups.The first type was hard nuclear cataract(≥ Ⅳ grade):24 eyes of 22 cases using dispersive and cohesive viscoelastic materials in ndocapsular phacoemulcification served as study group and 20 eyes of 20 cases using only cohesive viscoelastic materials acted as control.The second type was soft nuclear cataract(≤ Ⅲ grade):28 eyes of 25 cases using dispersive and cohesive viscoelastic materials in endocapsular phacoemulcification served as study group and 28 eyes of 24 cases using only ohesive viscoelastic materials acted as control.The corneal edema was observed one day after operation and the endothelial cell density was measured before operation and one month after operation.Results: There was statistically significant differences in corneal edema between the two groups in the first type(P<0.01);the difference was not statically different in the loss of corneal endothelium(P>0.05);there was no statistically significant differences between the two groups in the second type(P>0.05).Conclusions: Use of bilviscoelastic materials in hard nuclear cataract phacoemulcification could protect corneal endothelium and decrease coneal complications.