The invention discloses an inlet air temperature output device of an electric injection system. Based on characteristics of the inlet air temperature and the relationships between the inlet air temperature and time and the water temperature, the inlet air temperature is similarly simulated, and calculation of the inlet air temperature under three different working conditions of engine long-time stopping, engine short-time stopping and engine after-starting when an engine is started to be started is considered; when the engine is started to be started under the long-time stopping working condition, the water temperature, the inlet air temperature and the environment temperature are equal, and a value of the water temperature is taken as the environment temperature and the inlet air temperature; under the short-time stopping working condition, a decreased value of the inlet air temperature is calibrated and determined, the increased temperature after starting is used for integration of time, and the speed of integration is influenced by the environment temperature and the engine rotating speed. According to the inlet air temperature output device of the electric injection system, a signal of the inlet air temperature of the engine is calculated and obtained through a model, an inlet air temperature sensor is saved, the system cost can be reduced, the inlet air temperature can also be accurately obtained, and the different working conditions can be adapted.