Abstract:The development of power grid planning has changed from the original extensive to the intensive, which has made equipment utilization significantly affect economic performance. In order to improve the utilization rate of the equipment, this article has introduced the concept of simultaneous load of industries,from the perspective of improving the accuracy of maximum load forecasting,summed up in many existing load prediction method of induction, and the analysis of the typical daily characteristic curves between inter industries. and introduces the concept of inter industry load rate at the same time, A method for adjusting the maximum load of a subarea that takes into account the simultaneous rate between inter industries has been proposed. This method puts forward that there are also differences between peak load periods of different inter industries. That is to say, by modifying the maximum load forecast value through the inter industry simultaneity rate, a more accurate maximum load prediction value can be obtained. The calculation example of the theoretical demand of the line at the end of the paper shows that the maximum load forecasting method taking into account the simultaneous rate among industries can improve the accuracy of the maximum load forecasting, improve the utilization rate of the equipment, and the economical operation efficiency of the power system. The research results have great guiding significance for the economical operation of distribution networks.