The large-scale integration of distributed photovoltaic power sources makes the traditional short-circuit current calculation method no longer applicable. In this thesis, the quantitative analyses of both the grid-connected point voltage and fault output current of the photovoltaic power source are firstly applied to modify the photovoltaic power supply fault equivalent model considering the low voltage ride-through in order to make it more suitable for practical engineering calculations. Based on this, the short circuit fault equivalent circuit of the distribution network is decomposed into a power supply non-mutation network and a power supply abrupt network by means of the superposition principle into. The thesis then puts forward an improved calculation method for short-circuit current of distributed photovoltaic power distribution network. Finally, the proposed method is proved to be accurate and timely with the analysis of the simulating calculations and data.