The invention relates to a variable cycle power quantity settlement method and a system thereof, which divides power quantity data into time-varying power quantity according to a preset time interval;according to the start and end time of the settlement task, the time-varying electricity quantity is settled in a variable period., and according to the service specificity and data requirements of the price adjustment settlement in advance and the price adjustment settlement in afterwards. Through the preprocessing of all settlement-related data, the power settlement of arbitrary start time andend time can be completed under the guidance of the settlement task configuration, which is suitable for the unpredictability of price adjustment settlement and the characteristics of multi-time period.