A mathematical model of the multi tilting pad journal bearings in terms of thermal elastohydrodynamic lubrication(EHD)was established,and the transient lubrication performance of multi tilting pad journal bearings was analyzed.The orbit of shaft center from initial position to equilibrium position was obtained with full numerical simulation,and the lubrication performance at equilibrium position was studied,including film thickness,hydrodynamic pressure,temperature and thermal distortion and elastic deflection of pad face.The results show that the shaft center needs a quite long time to achieve the equilibrium position,and thermal distortion has a greater influence on the lubrication performance compared with the elastic deflection under a light load.