Objective To study the Xiaoyin No.2’ effect of content on the ear skin histopathological and proliferating cell nucleus antigen（PCNA） in psoriatic lesions of guinea pig. Methods 48 healthy guinea pigs were randomly divided into blank group， model group， angelica Yinzi（9. 88 g·kg-1）， Xiaoyin No.2 high， medium and low dose group（26. 7 g·kg-1， 13. 4 g·kg-1， 6. 68 g·kg-1）. 5% propranolol induction method was adopted to establish the guinea pig model psoriasis samples， for building 3 weeks after each group started by ig， the blank group and model group were given saline ig， for 2 weeks. Detection of guinea pig ear tissue Baker score， lesion of PCNA content. Results Xiaoyin No.2 high， medium and low dose group and angelica Yinzi histopathological grading Baker[respectively（3. 200±0.570）， （2. 600±0.418）， （2. 750±0.524）， （3. 000±0.447）] were lower than that of model group[（4. 643±0.476）]（P<0.05）；Xiaoyin No.2’ high， medium and low dose group of PCNA content[（14. 645±0.751）， （14. 153±0.899）， （14. 918±0.652）] were lower than that of model group（16. 889±0.883）（P<0.05）. Conclusion Xiaoyin No.2 can play a role for the treatment of psoriasis by improving the histological pathology score and inhibit the expression of PCNA.