Abstract: By means of linear regression analysis technique,the single regression model and multiple regression model between dynamic resistance information in spot welding process of mild steel and quality parameters are studied systematically.Results show as follows: (1) The total linear relations of all models are obvious by statistic test,which shows that the regression models can be used for monitoring and controlling spot weld quality.(2) The determination coefficients of the single regression model are only from 0.15 to 0.33,and the determination coefficients of the multiple regression model can be raised from 0.59 to 0.79,which show that developing multi-variable synthetical monitor is an effective way to raise monitoring accuracy.(3) The relations between monitoring information and quality factors are substantially non-linear,it will make model more error to describe such relations by linear model.