The invention discloses a transient temperature field simulation method based on multiple commutation failures of a smoothing reactor. The method comprises the following steps that A, an oil immersed type smoothing reactor three-dimensional geometrical model is built in a solid modeling mode on the basis of ANSYS finite element software; B, an oil immersed type smoothing reactor is subjected to heat generating analysis; C, the oil immersed type smoothing reactor is subjected to heat radiation analysis; D, the boundary conditions of temperature field simulation calculation are determined; E, the steady temperature field of the smoothing reactor under the normal work condition is calculated; F, the obtained steady temperature field result is used as an initial value of a failure transient model, then, the failure current is loaded, a step-length method is adopted, the distribution of the temperature field along with time after the failure is calculated, and the transient temperature field simulation method based on multiple commutation failures of the smoothing reactor is completed. The method has the advantage that basis is provided for checking the maloperation reason of a smoothing reactor gas relay and setting the gas checking setting valve of the smoothing reactor.