Abstract: With the purpose of investigating the characteristics of heat transfer between high temperature liquid and water, the film boiling process from hot sphere surface was analyzed by an improved boiling model and free surface tracking method. The results show that, when the temperature of sphere is constant, the film thickness increases from stagnation point of particle, the temperature contribution decreases with non-linear posture and the velocity contribution is parabolic in film. With the increase of initial temperature of sphere, both the film thickness and peak value of vapor velocity raise, while the overall heat transfer coefficient decreases. Meanwhile, the numerical technique captures the evolution of instability at interface and the process of bubble growing, which reveal the dynamic process of boiling clearly.