The invention discloses a reactive power configuration method and system under different cabling rates of a regional power grid. The reactive power configuration not only needs to meet the requirements of the regulations and specifications, but also needs to solve a new power grid situation where the cabling rate is increasing gradually. The method is characterized by, to begin with, calculating cable and overhead charging power of the regional power grid; then, judging reactive power of the regional power grid according to the calculated reactive power loss and reactive power supply information of the regional power grid; on the basis of analysis of the voltage level and power factor of the regional power grid, providing reactive power allocation schemes for different types of regional power grids; and checking the reactive power allocation schemes based on indexes of voltage fluctuation and reactive power allocation rate and the like obtained through simulating calculation to determine a final reactive power allocation scheme. The method and system can guide the reactive power configuration of the regional power grids under different cabling rate levels conveniently, are applicable to check of the reactive power configuration of the existing regional power grid and are also applicable to planning reactive power equipment construction and arrangement of the regional power grids.