The invention provides a method and equipment for measuring power generation efficiency of a photovoltaic power generation system. The method includes measuring voltage, current, temperature and radiancy of a photovoltaic module in the photovoltaic power generation system; acquiring equipment information of the photovoltaic module and preset coefficients of the photovoltaic module; determining power generation efficiency of the photovoltaic module according to the voltage, current, temperature, radiancy, equipment information and coefficients; measuring voltage and current of the input end as well as the output end of a combiner box in the photovoltaic power generation system; determining transmission efficiency of the combiner box according to the voltage and current of the input end and the output end of the combiner box; measuring power of the input end and the output end of an inverter in the photovoltaic power generation system; determining conversion efficiency of the inverter according to the voltage and current of the output end of the combiner box as well as the power of the input end and the output end of the inverter. Operation conditions of the whole photovoltaic system are known in real time, and system loss is reduced.