The utility model relates to a boats and ships technical field, concretely relates to boats and ships CNG pressure energy utilizes system and boats and ships, CNG storage tank, vortex tube, heat transfer device, natural engine and circulating water device, wherein, the CNG storage tank is connected with the vortex tube, and the CNG storage tank inside CNG flow in in the vortex tube, circulating water device and heat transfer device are connected for it is connected to convert CNG's pressure energy to vortex tube and heat transfer device cold, heat energy, heat transfer device and natural gas engine are connected, get into natural gas engine through heat transfer device heat exchange CNG later and burn. The utility model provides the high utilization efficiency of CNG fuel has reached the effect of utilizing CNG pressure energy.