As an important part of Liquid Crystal Display (LCD), polarizer has a direct effect on display quality.We made global heating and local heating experiments on polarizer used in LCDs.When the polarizer was globally heated, there was no light leakage.While in local heating, light leakage appeared on the polarizer with higher temperature gradients when center temperature is the same.The finite analysis model of the polarizer was established.The simulation results show that: 1) There is no shear stress on the polarizer when globally heated;and 2) The shear stress in the local heating test with small temperature gradient is far smaller than that in the test with large temperature gradient.Therefore, the shear stress is the main cause of light leakage.Reasonable design should be made on heat dissipation and structure on LCD to avoid shear stress.