<p>The comprehensive analysis of the constitutive relationship of the shear behavior of rock joints is crucial for predicting geologic hazards and ensuring the stability of underground engineering. This study investigates the full-process shear stress-strain relationship of sawtooth joints, with a particular focus on the residual stage, which has been largely overlooked in previous research. Through numerical simulations, the shear stress-strain curves of sawtooth joints under various sawtooth inclination angles and normal stress conditions are analyzed. The study reveals that the complete stress-strain curve consists of four distinct stages: shearing compaction, elastic, softening, and residual stages, with the residual stage exhibiting cyclic oscillations under certain conditions. A novel constitutive model is proposed to accurately describe the entire shear process, especially the residual stage, by integrating the effects of sawtooth inclination and normal stress. The model’s validity is confirmed through comparisons with experimental data from the literature. The development of a comprehensive constitutive model that fits the entire shear stress-strain curve, providing a more accurate representation of the shear behavior of sawtooth joints. Simultaneously, the derivation of functional relationships between peak strength, residual strength, and sawtooth inclination angle, offering new insights into the shear mechanics of rock joints.</p>