With the continuous increase of photovoltaic power generation installed capacity, accurate analysis and calculation of photovoltaic fault output characteristics have become the key to the safe operation of power systems. The control of inverters directly affects the fault behavior of photovoltaic power generation systems. When an asymmetric short-circuit fault occurs in the power grid, the existing photovoltaic short-circuit current calculation methods do not consider the transient process of the phase-locked loop and ignore the impact of phase-locked deviation on the short-circuit current, which may result in significant errors. To this end, the transient response of photovoltaic positive and negative sequence control under power grid faults is analyzed, the expression of positive and negative sequence AC and DC axis currents is derived, the tracking characteristics of currents are analyzed, and a calculation method for phase locking deviation under asymmetric power grid faults is further proposed. The influence of phase locking deviation on photovoltaic short-circuit current in the positive and negative sequence control process is analyzed, and the expression of photovoltaic positive and negative sequence current in the positive and negative sequence rotating coordinate system is derived. The calculation method of photovoltaic short-circuit current is obtained, and the correctness of the proposed photovoltaic short-circuit current calculation method is verified through simulation analysis.