In order to regulate the behavior of large shareholders selling, the CSRC issued the ‘Reduce Regulations’ for two consecutive years in 2016 and 2017. In order to verify the implementation effect of the ‘Reduce Regulations’, the changes in the probability, proportion and quantity of the large shareholder’s illegal selling before and after the promulgation of the ‘Reduce Regulations’ were studied to explore the regulatory role of the issuance of regulatory regulations on the shareholder’s selling behavior. The empirical analysis shows that the ‘Reduce Regulations’ has a significant inhibitory effect on the proportion and quantity of large shareholders illegal selling, but does not reduce the probability of illegal selling. Reviewing the policy effects of the two ‘Reduction Regulations’ in 2016 and 2017, it is found that the effect of the ‘New Regulations’ in 2017 are slightly more significant than that of the regulation in 2016. Further research found that the ‘Reduction Regulations’ has a significant restraining effect on the proportion and quantity of non-controlling large shareholders illegal selling, but failed to effectively reduce the proportion and quantity of controlling large shareholders illegal selling. The ‘Reduction Regulations’ can also greatly reduce the proportion and quantity of large shareholders illegal selling of companies in Small and Medium market, but it has not played a positive role in companies of Main Board Market and Growth Enterprises Market. Further study reveals that only a little evidence proves that the new regulation of 2017 is more effective than the old regulation of 2016 in the above reduction.