Abstract: The rapid development of flexible direct current transmission technology has further improved the reliability requirements of Press-Pack IGBTs for converter valves. The current researches on the reliability life model of Press-Pack IGBTs are insufficient. On the one hand, most models do not fully consider contact problems: the physical model is a welding form or a non-slidable combination, which does not conform to the physical mechanism. This makes the reliability model inaccurate and cannot truly reflect the actual situation. On the other hand, the fitting method of the analytical life model cannot completely decouple the single control variable, and the single variable fitting curve cannot accurately reflect the relationship between the variable and the reliability life. In this paper, we established a power cycle calculation model which considers all contact problems. We introduced pressure as a new variable for the packaging characteristics of Press-Pack devices and proposed a multivariate life model using an improved multiple linear regression fitting method. This analysis method can be applied to evaluate the reliability of Press-Pack IGBTs under power cycle. Through the finite element calculation, it is verified that the multivariate life model is more accurate than the univariate fitting.