In order to investigate the effect of multi-dimensionless parameter variations on heat transfer efficiency and mechanism during spray cooling, the free energy lattice Boltzmann method was used to investigate the heat transfer process of van der Waals fluid droplet impacting on a superheated surfaces, the effects of superheat, wettability, Weber number(1 ~ 100), and Reynolds number(50 ~ 1 600) on the droplet morphology and heat transfer mechanism were analyzed. The results show that with the increase of superheat, the heat transfer increases almost linearly to the maximum value, and then decreases rapidly. The droplet can undergo five stages, namely, single-phase heat transfer, nuclear boiling, transition boiling, transition boiling with droplet breakup and film boiling. When the Weber number is small, the droplet does not break, and some microbubbles will appear inside the droplet, and eventually merge into a larger bubble, the maximum heat transfer mainly occurs in the nuclear boiling stage. When the Weber number is large, there are two mechanisms of droplet rupture: droplet evaporation and droplet spreading and shrinking. After the rupture, the daughter droplet will escape from the superheated surface and reduce the heat transfer, the maximum heat transfer occurs in the single-phase heat transfer stage. When the hydrophobic surface is transformed into a hydrophilic surface, the heat transfer increases rapidly, and nuclear boiling is easy to occur under hydrophilic conditions, and inversely, film boiling occurs. When the Reynolds number is small, the heat transfer increases with the increases of both Weber number and Reynolds number. When the Reynolds number is large, the heat transfer first increases and then decreases with Weber number increasing. In the range of parameters studied, the heat transfer and the product of Weber number and Reynolds number are approximately logarithmic.