Security analysts, as the external supervisors, play a role in external corporate governance，thus having an impact on the audit services of CPA. Taking the A-share listed companies’ data in Shanghai and Shenzhen Stock Exchanges from 2010 to 2013 as sample, this paper makes an empirical research on the relationship between focus of security analysts and audit fee on the basis of the modified Simunic model. In addition, this paper divides samples chosen into samples of state-owned enterprises and non state-owned enterprises and makes a research on them respectively. The results show that focus of security analysts is negatively correlated with audit fee. In comparison with private enterprises, the relation between the focus of security analysts and audit fee is more negatively correlated in state-owned enterprises.