Objective To explore the biomechanical responses of oral mucosa under the effect of spherical bracket and conventional bracket by three-dimensional (3D) finite element analysis. Methods The 3D finite element model of lip-incisor-bracket was established. Four simulated cases were designed according to different arrangements of central incisors, and the stress and strain of the moving upper lip under the effect of spherical bracket and conventional bracket was analyzed numerically. Results The maximum stress of spherical bracket on oral mucosa was higher than that of conventional bracket when the tooth was aligned. The maximum stress of conventional bracket on oral mucosa was higher than that of spherical bracket, when the incisor was mesially rotated by 15°and 30°, as well as labially misaligned by 15°, respectively. Conclusions Compared with square conventional bracket, spherical bracket with smooth shape is more suitable for the functional movement of oral soft tissues in orthodontic patients with misaligned teeth. It is suggested that shape design of conventional brackets should be improved to reduce mechanical response of oral mucosal tissues.