The invention provides a power plan feasibility check method and system. The method comprises the steps that installed capacity and maximum output power of each generator set are obtained, and a load rate upper limit and a load rate lower limit of each power plant are obtained; maximum power generation load and the standby quantity are obtained every day; power generation planned value of each power plant is obtained; maintenance days and standby days of each generator set are obtained, and the on days of each generator set and the set of generators which can be on every day are obtained, load rates of operating generator sets of all the power plants are determined; a peak balance margin in a planned time period is determined every day; a set of power plants with power planes required to be adjusted is determined; whether the power plant is empty is judged, if yes, the power plan is feasible, otherwise, the power plan is infeasible. An effective tool can be provided for reasonable design of the power plan.