The mathematical model of optimal allocation of capacitor for distribution network is firstly established so to take maxixum annual economy efficiency after compensating reactive power as objective function.The compensation capacitor is

in consderation of load variation of distribution network

the cost of capacitor and discrepancy of capacity

divided into the fixed capacitor and switching capacitor to suit the need of reactive power compensation at different load and reduce the investment cost.Then

the optimal allocation program of capacitor of distribution network based on heuristic strategy and genetic algorithm is prepared by VC and optimal allocation of the capcitor of the IEEE 69 bus system is made.In case of allocation

only such two different compensation mode as fixed capacitor and fixed capacitor plus switching capacitor.It is shown in the optimal result that the use of fixed capacitor plus switching capacitor can better suit load variation

can meet compensation capacity need in heavy load and prevent over compensation at light load.