To meet the requirements of accommodating new energy sources and balancing power supply and demand, a new type of power system dominated by new energy sources needs to maximize the load-side regulation capability. To address the problem of insufficient exploitation of load-side regulation capability, this study proposes an electricity load optimization method based on an interactive real-time electricity price mechanism. Firstly, a generalized benchmark new energy output curve is established based on the total new energy within a regional power grid. Secondly, a source-load similarity calculation method based on improved time series morphological similarity is proposed to calculate the similarity between electricity load and the generalized new energy benchmark curve, and a model for the correlation between load and electricity price is constructed. Then, an interactive real-time electricity price mechanism based on source-load similarity is proposed to guide user participation in response. Finally, a multi-objective optimization model is constructed for load optimization. Simulation results show that the proposed interactive real-time electricity price mechanism achieves better load optimization results, effectively increases user participation in demand-side response, and accurately measures the similarity between new energy and load curves. This approach stabilizes the net load power and promotes the high-quality integration of new energy.