The invention provides a regional power grid reactive power optimization control method based on an incidence matrix. The method comprises the procedures of designing the incidence matrix of an equipment status and carrying out time internal division accordingly. On the basis, static reactive power optimization is carried out on each time period, the optimal solution and part of second-optimal solutions of each moment are kept, the solutions are used as status variables of dynamic programming, and an optimal path is searched in each time period by using a dynamic programming method with the target of minimum action times, thus obtaining the solution of the problem of dynamic reactive power optimization of the whole dispatching cycle.