Endothermic effects in desorption process of natural gas vehicle tank seriously affects the gas desorption efficiency and vehicle speed.In this paper,a numerical model in desorption process of heating natural gas vehicle tank by engine cooling water was established,and by which the desorption processes were calculated.It shows that when the tank is heated by the engine cooling water,the rising of temperature makes the desorption amount of natural gas increased obviously.Also,the increasing of diameter of internal cooling pipe and thermal conductivity of adsorbent can increase the desorption amount.