Abstract <p>The shear property of rock joint surface considering physical weathering and long-term shear is rarely concerned. Based on the widely developed slate rock mass in the Miaowei Reservoir area of Yunnan Province, China, six groups of slate rock joint surfaces are prepared to suffer cyclic wetting-drying test first and then cyclic shear test, so that these slate rock joint surfaces can experience different degrees of weathering and long-term shear; based on the tests, the relations among peak shear strength (τ), cohesion (<i>C</i>), friction angle (ϕ), wetting-drying cycle (<i>C</i>_{<i>W</i>-<i>D</i>}), shear cycle (<i>C</i>_<i>S</i>) and usual normal stress (σ_<i>n</i>) are studied. Besides, an estimation model of τ of rock joint surface is proposed by quantifying the effects of physical weathering and long-term shear with damage variable (<i>D</i>) and joint roughness coefficient (<i>JRC</i>), respectively, and the proposed estimation model is finally applied to the stability evaluation of a bedding slate rock slope. The analytical result mainly indicates that the long-term shear weakens the slate rock joint surface to a residual state instead of infinite weakening, and the physical weathering tends to shorten the weakening process; the proposed estimation model shows a better estimation effect compared with the typical estimation model, and for practical application, the theoretical calculation method and estimation method of parameters in the proposed model are also given; the engineering application result based on the proposed estimation model reveals the stability evolution process of one bedding slate rock slope under continuous degradation, and as a reference for the bedding slate rock slopes with similar engineering geological conditions in the Miaowei Reservoir area, the related stability evaluation result may be obtained quickly through a set of on-site Schmidt hammer tests.</p>