Housing provident fund, as the main part of China urban housing security system, provides the housing security mainly by drawing and loans. This paper estimates the total difference, regional difference and area inner difference through the estimation and decomposion of theil index. The results show that there exists very big difference in housing security development of Jiangsu housing provident fund, and its determinant is the big gap among southern Jiangsu, middle Jiangsu and north Jiangsu. This paper suggests that the government should pay attention to area coordinated growth and take different measures according to circumstances in the implement of housing provident fund.