The islanding detection technology can guarantee the safe operation and stable operation of the inverting photovoltaic power generation system in connection with the power system. Based on the analysis of the traditional method of reactive current disturbance, this paper presents an improved frequency positive feedback method for reactive current disturbance islanding detection. Through the periodic application of the reactive disturbance current and the positive feedback function of the disturbance function, the amount of reactive disturbance is increased to limit the frequency, so as to achieve the anti-islanding effect protection function. The simulation model was built by Matlab/Simulink simulation software. The experimental results show that this method has little influence on power quality and does not inject harmonics into the power grid. It has the advantages of no detection blind zone and fast detection speed.