By selecting a sample of A-Share listed firms from 2008 to 2011, this paper tries to investigate the effect of environment uncertainty on the cost of capital and the governance effect of the internal control. The main findings are as follows: The relationship between environmental uncertainty and the cost of capital is positive and high quality internal control helps to alleviate the tension of the above positive relationship, especially for the companies held by institutional investor specialization, the effect of high quality internal control to alleviate such relationship between environmental uncertainty and the cost of capital is greater. Further inspection also found that, compared with other elements of internal control, excellent internal control environment can significantly relieve the positive relationship between environmental uncertainty and the cost of capital.