Supposed disc surfaces have initial disc thickness variation (DTV) with 2 order sine function characteristics, a FE model of ventilated disc brake for transient thermomechanical coupling simulation was established. With the distribution of the temperature, the normal stress and the elastic deformation on disc surfaces for the evaluation, the influences of the initial DTV and its direction and maximum on thermomechanical coupling characteristics were analyzed. The simulation results show that the temperature, the normal stress and the thickness variation have a 2 order sine function characteristic in circumferential direction, which is the most important difference between the thermomechanical coupling characteristics with and without the initial DTV. The 2 order sine function distribution in circumferential direction is related with the initial DTV direction and tendency. With the initial DTV, the distribution of the temperature, the normal stress and the elastic deformation in radial direction tend to be uniform. The circumferential gradient maximum of the temperature, the normal stress, the disc distortion and thickness variation increase with the initial DTV maximum increasing.