The invention belongs to the technical field of the reactive voltage control over a power grid and more particularly relates to a reactive voltage verification method based on a limit operation mode. According to the method, firstly, through reading the data information of the power grid, four operation modes are formed, and then a limit operation mode is selected based on the calculation result of a comparison voltage. Secondly, a substation of the worst voltage exceeding condition is selected, and whether the two-side / three-side voltage of a substation transformer exceeds a voltage upper limit Umax or a voltage lower limit Umin or not is examined. Thirdly, a compensation factor epsilon is set and the amount of reactive power compensation QC / QL of the substation is calculated. Fourthly, whether the sum of the amount of reactive power compensation QC / QL and the actual input QCr / QLr of the reactive power compensation exceeds a pre-configured capacity QCmax / QLmax of the reactive power compensation or not is judged. Fifthly, the voltage is re-calculated based on the above adjustment. The above process is circularly conducted till no voltage exceeds the upper / lower limit. According to the invention, based on the calculation of limit operation modes, whether the configuration status of reactive power compensation equipment meets the requirements of the relevant provisions and the requirement of voltage adjustment or not can be effectively verified, so that the decision-making process of the power grid operation is guided. Meanwhile, the blank in reactive voltage checking method is filled, and the above method is more applicable to the actual operation status of the power grid. Therefore, the method is suitable for online application.