The factors of vehicle LCD high temperature crosstalk in reliability test were studied. It was found that the bigger the N+ step remain of TFT channel was, the worse the high temperature crosstalk became. The N+ step remain could be improved by increasing ashing time of N+ etch process. Thickness of gate insulator would also affect the crosstalk. The DOE experiments show that the significant factors affecting reliability crosstalk are N + step remain of TFT channel and thickness of gate insulator.