The random fractal model is firstly put forward to simulate the drop size and spatial distribution in dropwise condensation. The boundary conditions of heat conduction through the condensing wall surface are then established using the heat transfer model through a single drop proposed by J.W. Rose. A numerical method towards the directed simulation of dropwise condensation heat transfer is presented. The model considered the effect of the nonuniformity of surface heat transfer thermal conductivity of the condenser material on dropwise condensation. Numerical computations are conducted for dropwise condensation heat transfer of water on the copper wall on a very wide range of pressure. The numerical simulation results agreed well with the bulk of existing experimental data and the precision is higher than the model proposed by Rose.