Abstract: In recent years,with the rapid increase in the number and installed capacity of grid connected PV power stations,PV power generation has had a significant impact on the stability and safe operation of the power grid. In order to ensure the stability of the power grid,reactive power compensation devices have become one of the essential equipment for PV power stations. However,in actual operation,it has been found that most PV power stations have the problem of excessive allocation of reactive power compensation capacity,leading to an increase in project investment costs. This paper focuses on the configuration of reactive power compensation capacity for typical complex mountain PV power stations. Considering the special nature of the collection and transmission line projects,combined with the economic feasibility of PV power station construction,the calculation method of reactive power compensation capacity has been improved in the line engineering design stage through theoretical calculation and analysis,and comparative calculations are conducted.The research results show that:1) Increasing the cable laying length of the transmission line,reducing the length of the overhead transmission line,and segmenting the load calculation of the collection line can all reduce the reactive power compensation capacity configuration of the PV power station. 2) By adopting the improved calculation method,the PV power station can save hundreds of thousands of yuan in initial investment and increase the overall revenue of the PV power station.