The working temperature has great effect on the reliability of LED modules. In this paper, numerical analysis is carried out on predicting the temperature field in a LED module based on simplified two-dimensional model. It is found that the highest temperature manifests in the LED chip and more than 99% of the heat generated by the LED chip are transferred out through the copper heat sink. Parametric study shows significant temperature increment from 327K to 384K in the LED lighting chip by decreasing 10 times of the thermal conductivity values of conductive layer from 24.5W/(m.K) to 2.45W/(m.K). It is concluded that the key factor in heat transfer process inside the LED module is the thermal resistance of the thermal conductive layer lying between LED chip and copper heat sink.