<p>The shear deformation of rock discontinuities plays a crucial role in the stability analysis of engineering rock masses. The damage constitutive model combining statistical damage theory with damage distribution is a prevalent method for studying the shear deformation of geologic materials. However, conventional models often rely on empirically selected damage distribution, neglecting the intrinsic uncertainty associated with the distribution function. To solve this problem, a generalized distribution function based on maximum entropy theory is established. Following this, a novel shear constitutive model of rock discontinuities is proposed. Many experimental data, encompassing laboratory and in situ tests, validate its credibility. Comparative analyses with four classical models further demonstrate the model’s robustness and adaptability. Finally, the engineering application of the model and its applicability to the shear deformation of the rock-concrete interface are discussed. The findings indicate that the proposed model exhibits professional competence in simulating the shear deformation of rock discontinuities, notably characterizing the deformation traits across each stage. It displays superior accuracy against comparable models, as substantiated by superior R², RMSE, and AAREP values. This paper introduces a novel approach utilizing maximum entropy theory to investigate the shear deformation of rock discontinuities, offering geoengineers a strengthened tool for assessing the shear behavior of such discontinuities.</p>