Building cash flow at the core of the financial security index system, based on corporate cash flow statement provides financial information, as a sample of the 128 companies in the Shanghai and Shenzhen Stock Exchange, China's real estate industry, data from the 2011 published Annual Report. The KMO test the correlation of financial indicators and Bartlett's test of sphericity factor analysis, results show that the index has a strong correlation. With SPSS18.0 software, principal component analysis, seven principal components factor, and the cumulative variance of the seven factors of 73.821%, more complete description of the seven indicators retained the original data of the amount of information, proof of financial security affect factor rationality.