On the basis of the research results published in existing relevant references,the logistic curve methodis are further improved and a new power load logistic curve-forecasting model is proposed based on improved particle swarm optimization(IPSOLM). And the result of the Power load gray-forecasting model based on particle swarm optimization (PSOGM) compares with the result of the new power load forecasting model. The practical example indicates that the new model has the characteristic of better precision and wider application field.