A comprehensive investigation to the risk factors of breast cancer was carried out in 146 pairs of women subjects, with the method of 1:1 matched case-control study, and of logistic regression analysis and principal component analysis. As a result, a regression equation which includes 5 independent variables has been established by logistic regression analysis; Ten principal components were extracted from 22 risk factors of breast cancer through principal component analysis, and the cumulative contribution of variances of the 10 principal components is 64.8%. The result combining the mono-factor analysis and the multiple variables analysis indicated that the principal risk factors of breast cancer are cadre occupation, the age of primiparity and late marriage, more intake of salted meat and sausage, passive smoking, having the history of family tumor, of breast benign tumor, and of the mastadenitis; but the more number of giving births, longer period of time of lactation, more vegetable intake, and taking more vitamin may have preventive effect for breast cancer.