Power measurement is an important part of solar photovoltaic power generation system. This paper presents a photovoltaic power generating capacity detection system that consumes less energy,lower cost and gives a more precise value. The system uses AVR single chip computer as the controller,avoiding consumption of analog-digital conversion and others,and simplifying system structure.At the same time,Hall current sensor is used to change current signals into voltage signals with least energy consumption. The experimental results show that photovoltaic power generating capacity can be displayed on the screen in real time,and the error rate will not exceed 5% when working.