Aiming at the ratio of photovoltaic array power to pump power in practical engineering applications, the influencing factors of light intensity and installation angle of photovoltaic panels in Shaanxi are analyzed. And combined with the designed inverter efficiency of the PV pump system, it is calculated that the optimal power ratio range between PV array power and pump power in the PV pump system in Shaanxi is 1.265~1.536, providing reference for the construction of solar photovoltaic water pumping project in Shaanxi.