Running state before the failure will affect the short-circuit current of doubly fed induction generator (DFIG) which operates in low voltage ride through, and the speed of the wind turbine is a very important factor. Considering the crowbar circuit, based on the conservation of flux, this paper derives the expression of short-circuit current when three-phase short-circuit fault occurs. A detailed analysis of how the slip affects the short-circuit current’s characteristics from the periodic component, the DC component and speed transient attenuation frequency components is made. And PSCAD is used to build a 30 kW double-fed wind turbine model, the simulation results verify the theoretical analysis is correct. The conclusions provide a theoretical basis for more in-depth analysis of failure characteristics of DFIG and factors of the short-circuit current. It is conducive to the research of protection setting computing.