The invention discloses a control method for improving device performance of an electronic temperature controller. The control method is characterized in that protection judgement is given and/or working voltage of a relay is adjusted through detecting the working voltage of a compressor. According to the control method, through detecting the working voltage of the compressor, protection judgement is given; and the working voltage of the relay is also adjusted according to the measuring voltage, so that the energy is saved and the environment is protected, and the service life is prolonged.