For the prediction and control of mechanical property of laser tailor-welded blanks, combining it′s microstructure-property rule microstructual qualitative analysis of joint microstructure of 0.8~1.5 mm St12 steel and galvanized steel sheet is constructed. The predominant influencing factor is martensite content and the optimal control process is obtained. On the basis of the research, prediction models of mechanical properties of tailor-welded blanks trained with welding processes and sheet thickness as input variables are put forward based on partial least-squares regression. According to the testing results, the forecasting accuracy of tensile strength and elongation is above 91%. Therefore, the proposed models are reasonable and applicable to examine deep-drawing steel for demonstrative purposes.