This paper proposes a comprehensive consideration of the actual working condition of MMC lifetime prediction method .Zhoushan data run month in a year as a mission profile processing, task stress profile is converted to electricity, the electric stress task profile as input.Based on the loss calculation, the electric heating model and the life model are used to predict the life of IGBT and capacitor, and finally obtain the MMC life.It is concluded that the analysis of the key factors affecting the service life of the MMC system results consistent with the actual operation condition.