The invention provides a peak load shifting control method and system and a system of using the peak load shifting control method. The peak load shifting control method comprises the steps of solvingvariable control parameters in a preset variable parameter power difference control strategy on the basis of a pre-built peak load shifting model and typical daily load forecast corresponding to a current day; and introducing the obtained variable control parameters into the preset variable parameter power difference control strategy to achieve coordinated control on charging and discharging powerof an energy storage system. Compared with the prior art, the peak load shifting control method has the advantages that the variable parameter power difference control strategy is provided, the influences of energy storage on the peak load shifting effect and state-of-charge of a load side are coordinated and considered in the control strategy, and variable optimization is carried out on a normalworking upper limit state-of-charge of the energy storage system, a normal working lower limit state-of-charge of the energy storage system and charging or discharging power factors of the energy storage system in different load intervals and different state-of-charge (SOC) intervals, so that the charging and discharging characteristics of the energy storage system can be kept and the service life of the energy storage system is prolonged.