Objective   To investigate the effect of retinoic acid (RA) nanoparticle eyedrops as a therapeutic agent on prevention of posterior capsular opacification (PCO) and the toxicity of the drug. Methods   Eighteen New Zealand albino rabbits were divided randomly into three groups, followed by the extracapsular cataract extration(ECCE): Group A, control group; Group B, using RA nanoparticle eyedrops(300μg·ml  -1); Group C, using RA nanoparticle eyedrops(700μg·ml  -1).The changes of the posterior capsule were observed by slit-lamp microscope, ophthalmoscope and photography, and the toxicity of RA were evaluated. Results   At 12 weeks after operation, the occurrence of posterior capsular opacification was noticed in 10, 6, 4 eyes respectively in the 3 groups. The PCO score and PCO rate of the control group were higher than those of the RA group(P<0.05). Histological analysis showed that the proliferation in the control group was much more intense than that of the RA groups. The iris and ciliary body in the RA group did not produce chronic inflammatory. Conclusion   The RA nanoparticle eyedrops can inhibit metaplasia and proliferation of lens epithelial cells in rabbit eyes without obvious toxicity. It can be used as a potential agent in the prevention of the development of PCO.