The invention provides a data processing method of reactive voltage in an urban power grid and a data processing system. The invention conducts an analysis of the 220kV power grid reactive voltage, 110kV and below power grid reactive power releasing, 220kV power grid inductive reactive compensation, 220kV partition unit phase advance capacity, 500kV power grid reactive voltage and low resistance input voltage sensitivity by acquiring data during a light load period, and conducts an analysis of the 220kV power grid reactive voltage, 220kV power grid capacitive reactive compensation, 220kV partition power grid dynamic reactive reserve, 500kV power grid reactive voltage and voltage stability by acquiring data during a heavy load period. The invention realizes the reproduction of reactive voltage conditions of the urban power grid during the light load period and the heavy load period, determines the problems in terms of the voltage reactive operation and control in the urban power grid, and provides a basis for further improvement measures and recommendations.