Abstract: According to the analysis of the interaction of laser,powder and melting pool,a model of effective utility of laser power in process of powder feeding laser cladding is presented,and then calculation is performed with the parameters in process. It can be seen from the result that the amount of effective utility of laser power is small. The model objectively reflects the major relationship between the parameters and the results of process.It also provides a theoretical foundation for optimizing the process parameters,predicting and evaluating the quality of clad coating.