It is closely related between distribution network planning and the nature of the city land. Subarea load is calculated based on the nature of the city land, and combined with load forecasting, which can be used as a basis for load density forecasting of space load forecasting. It has practical value for improve the accuracy of load forecasting in distribution network planning. The least squares method and the similarity search method are used to study the situations of sufficient and insufficient sample datum in the actual planning, so that the load density prediction can follow the rules and be the prerequisite for the prediction of space load.