Taking intellectual property right policies system of promoting the capability of indigenous innovation as a subject, establishing mathematical model of BP Netual Net through MATLAB, the paper explores its effects on social welfare in China, so as to give some advices on how to promote social welfare in China. The author discovers that different policies have diverse influence on the direction and degree of social welfare. The paper concludes that the government should not only add up the number of the policies, but also strengthen the effort of the policies， should adjust the policy goals, promote the conflict coordination mechanism between policies, reform the measures of the policy system, and desalinate administrative intervention and utilizing policy tools of stimulating innovation.