To study the influence of joint dip angle on rock mass damage, the damage evolution model and damage constitutive model of jointed rock mass were built considering the combined action of joint and load based on damage mechanics theory. The model test was verified by the single weak surface theory, and the damage evolution characteristics of the jointed rock mass were investigated. Results showed that the theoretical results of single weak surface theory were in good agreement with the experimental results. The model test could better characterize the mechanical characteristics and damage evolution law of the rock mass with single structural plane under load. The initial jointed damage showed an inverted U-type distribution that it increased first and then decreased with the increase of the joint dip angle, and it reached the maximum value when the dip angle was 60°. The total damage curve showed an S-type distribution that it grew slowly first, then rapidly, and finally slowly approached 1. The joint dip angle only affected the magnitude of the total damage rate instead of its evolution trend. The total damage rate curve showed a normal distribution that it increased first and then decreased with the increase of the strain. The total damage rate was affected by the distribution of the joint plane, which decreased first and then increased when the joint dip angle increased from 0° to 90°.