Demand-side adjustable resources and demand response markets have multi-time scale characteristics, and with the reduction of decision-making time scales, the accuracy of load forecasting increases and the uncertainty of response decreases. In order to fully combine the advantages that long-time-scale decision-making can fully call various adjustable resources and short-time-scale decision-making with less uncertainty, this paper proposes a demand-side adjustable resource aggregation response strategy based on multi-stage decision-making. Specifically, a multi-stage demand response decision-making framework is constructed, a demand-side adjustable resource aggregation response model is established, and a multi-stage demand-side adjustable resource aggregation response model is formed. Based on this, the objective function considering aggregated response income and response deviation is set for each stage decision, and the solution strategy is designed based on the branch and bound method, forming a demand-side aggregated response strategy is proposed based on the branch and bound method. Finally, an example is used to compare the response effect of the demand response strategy applying single-stage decision-making and the strategy proposed in this paper, and it is verified that the strategy proposed in this paper can effectively improve the aggregate response capacity and response accuracy of demand-side adjustable resources.