From the view of investors protection，we use the segment data of Ashare Chinese listed companies from 2009 to 2011 to empirically examine the effects of corporate diversification and media on the quality of accounting information. We made a distinction between industry diversification and geographical diversification，as well as related diversification and unrelated diversification. We find that industry diversification will damage the accounting information quality，and this damage is mainly derived from unrelated diversification. On the other hand, geographic diversification is significantly positively correlated to accounting information quality. Furthermore，to solve the industrial diversification discount problem, we introduce an important external corporate governance mechanism media into the model. And the results prove that under the diversification circumstance，wellorganized media can improve the accounting information quality. Our research provides more evidence to the diversification discount or premium argument. In addition，we find a possible way to solve the diversification value destruction problem，which may be helpful for the regulators to do the related politics.