A random fractal model of the drop size and space distribution in dropwise condensation is presented.The boundary conditions of heat conduction through the condensate wall are defined by use of the heat transfer model through a single drop proposed by Rose.Thus,the mathematical model of dropwise condensation heat transfer is established.A numerical simulation of dropwise condensation heat transfer of water on the copper wall has been performed.The results agree well with the bulk of existing experimental data and the precision is higher than that of the model proposed by Rose.