The invention relates to the field of alternating-current ultrahigh voltage transmission and transformation engineering and design, in particular to a high-voltage shunt reactor compensation method for a typical ultrahigh voltage transmission line and discloses a high-voltage shunt reactor compensation method for an alternating-current ultrahigh voltage transmission line. The method includes the steps that a PSCAD-based electromagnetic transient simulation model of a system is established; the total charging reactive amount Qc and the high-voltage shunt reactor compensation amount Qg1 of the ultrahigh voltage transmission line with the length of 1 are determined; the requirements for inhibiting power frequency overvoltage generated by the no-load capacitance effect of the ultrahigh voltage line, power frequency overvoltage generated by load shedding of the line under the full-load condition and power frequency overvoltage generated by a single-phase earth fault of a low voltage side are comprehensively considered according to general rules of line high-voltage shunt reactor compensation, and finally the capacity Qg25 of a parallel high-voltage shunt reactor on the sending end grid side of the ultrahigh voltage transmission line and the capacity Qg15 of a parallel high-voltage shunt reactor on the receiving end grid side of the ultrahigh voltage transmission line are determined to arrange the parallel high-voltage shunt reactors of the ultrahigh voltage transmission line. The steady-state voltage adjusting characteristics of the system are considered, so that the load flow of a power grid and the voltage of the ultrahigh voltage transmission line are stably controlled to be within a more reasonable range.