In the context of China's economic and social transformation and upgrading and the new round of energy revolution, the behavior characteristics of power users will change, thus affecting the load characteristics of the power grid. This paper identified key influencing factors of user behavior from the perspectives of electric vehicles ("EV"), demand side response and distributed generation ("DG"), established the mechanism and model of user behavior affecting load characteristics, and took a region as a typical case to predict and simulate the comprehensive impact. The simulation results show that EV and demand side response will change the peak-valley difference rate of the load curve. With the continuous increase of the DG scale, the peak-valley period of the power grid load curve will change and gradually show the characteristics of duck curve. The methods and conclusions proposed in this paper have important reference significance for studying and judging the future load change trend.