A critical element for the incentive-based demand response (DR) programs is the determination of customer baseline load (CBL). Due to the informational asymmetry, traditional methods to determine CBL using historical data may cause manipulation problems, which have negative impacts on the efficiency of DR programs. A demand subscription model with informational asymmetry is presented based on the mechanism design theory. In this model, customers’ type parameters are introduced to describe their different willingness to increase load demand, and the individual rationality and incentive compatibility constraints are also taken into account. In addition, the solution is provided. The proposed model is helpful to solve the manipulation problems in demand subscription and can lead customers to voluntarily reveal their true CBL information. A numerical example is presented to verify the effectiveness and reasonableness of the model.