The invention discloses a distributed power supply allowed capacity calculation method considering a short circuit capacity constraint. The method includes: step 1, using a formula as described in the specification as an objective function, and using a node voltage deviation constraint, a node voltage fluctuation constraint, a short circuit capacity constraint and a power distribution network power flow constraint as constraint functions to build an optimization model of distributed power supply allowed capacity; and step 2, adopting a genetic algorithm to solve the optimization model, and an optimization result is distributed power supply allowed capacity. The distributed power supply allowed capacity calculation method considering the short circuit capacity constraint can obtain access capacity limits of distributed fans and distributed photovoltaic devices with different output characteristics, thereby providing a scientific decision basis for reasonable grid connection of distributed power supplies.