The invention discloses a step characteristics-based air-conditioning load-participated power grid day-ahead scheduling method and belongs to the field of the running and the dispatching of a power system. According to the invention, in the prior art, when the central air-conditioning system of a large building adopts the wheel stop control mode, the temperature of the large building cannot be accurately controlled. Meanwhile, the power consumption amount of the large building cannot be accurate, so that the day-ahead dispatching power generation amount of the power grid cannot be accurate. Inorder to solve the above problems in the prior art, the invention provides the above day-ahead scheduling method. The characteristic extraction technology of an air-conditioning load is combined withthe prediction technology, and a historical air-conditioning load is extracted. After that, a model for each heat load of the large building is established, and then a total heat load model is deduced. Meanwhile, the dispatching capacity of the central air-conditioning system of the large building is calculated. According to the dispatching capacity of the central air-conditioning system of the large building, the participation of the bid inviting is carried out and then a dispatching command of the power grid is completed. The peak-load shifting of the load is realized for the power grid side, and the safety and stability coefficients of the power grid are improved. For the user side, the electric quantity is saved, and the scheduling compensation provided by the power grid is obtained.As a result, the development tendency of the intelligent power grid to participate in dispatching is realized. That means, the coordination control of a user and a power grid is realized.