There are closely and interestingly economic ties between funds and the security firms with qualifi-cations of rating funds． On one hand，these security firms provide ratings for funds． On the other hand，funds may be economically connected with these security firms through the following two ways． First，funds pay trading commission fees to security firms since they need trading seats from security firms． Second，these secu-rity firms may be large shareholders of mutual funds． Then，will these two kinds of connected interests harm the independence of these security firms when rating funds? This paper finds that: 1) if there are trading com-mission fees or ownership relationship between funds and rating security firms． security firms offer higher rating for funds; 2) the rating under the shadow of connected interests has lower explanatory power for future fund performance; and 3) the above two effects are more significant after 2010 in which year the regulation system of fund rating qualification was enacted． Those findings show that connected interests damage the independ-ence of security firms as fund rating agencies，and the regulation system of fund rating qualification further exacerbates the damage．