Frictional loss is a key factor that influences the performance of fluid machine.In order to reveal the friction-wear mechanism and its influence factors，according to the configuration，compression process and force analysis of scroll fluid machinery，a prediction friction force fractal model for rubbing pairs with fixed and orbiting scroll faces was derived based on M-B fractal model，sliding friction force fractal prediction model and analysis of real microcosmic contact form and force of fixed and orbiting scroll faces.Verification and analysis of the model were made through an example.The results showed that there was an optimum fractal dimension of scroll surface，on this optimum fractal dimension，friction force was reduced with the decreases of G*and A*r，so the friction resistance would be reduced through improving the contact properties of fixed and orbiting scroll faces so as to enhance operational performance and prolong working life of fluid machine.