Spray cooling characteristics of TG6.5 solid cone nozzle are studied by building a liquid nitrogen spray cooling experimental bench. The relationships between the superheat and the heat flux as well as the superheat and the heat transfer coefficient near the critical point are analyzed. Then the influence of the spray area and the spray flow rate on the heat transfer effect is discussed. Results show that， in the process of heat transfer， with the increase of the heat flux， the change of superheat can be divided into three stages： a slow increase，an obvious increase and a sharp increase. Under the influence of bubbles in nucleate boiling， the superheat at the maximum heat transfer coefficient is less than that at the critical heat flux. Increasing the spray flow can significantly improve the heat transfer effect. Increasing the heat sink area will reduce the impact frequency and intensity of droplet particles in the unit area， so that the heat transfer effect will decrease.