Taking 502 firms in Shanghai and Shenzhen stock markets as the surveyed object, the correlation between the firms' information publishing and the cost of capital were tested empirically.  The results show that the conservative earning is negatively correlated remarkably to the capital costs in 366 firms that have adopted conservative earning policies, but the aggressive earning is not correlated significantly to the cost of capital in 136 firms with aggressive earning policies.  Thus the firms' effective information announcing can reduce the cost of capital, implying that the good corporate governance will be helpful to the good operation performances.