Electrical load forecasting is a complicated multilevel system including dimensions of space， time， attributes， etc. In order to solve the problem of multilevel load forecasting and coordinating， the basic coordinating model based on power system state estimation is proposed. By introducing the concept of forecasting credibility into this coordinating model， the coordinating results under different combination of credibility are compared. Furthermore， the mechanism of this basic coordinating model is illuminated by the concepts of adjustment coefficient and relative adjustment coefficient. In particular， the criterion for evaluating the performance of different coordinating models is also given. The situations where this basic coordinating model can be used are also pointed out. In conclusion， numerical example is used to validate the effectiveness of this novel coordinating model.