Aiming at the characteristics of roadway surrounding rocks in Baiyinhar mine, such as hard lithology, severe alteration and extremely poor stability, a secondary support scheme for the roadway based on the distribution of the plastic zones was proposed. For the fractured surrounding rocks, based on the results of the point load test and the relevant shaft construction data of the Baiyinhar mine, the physical and mechanical parameters of the rock mass were calculated according to the Hoek-Brown strength criterion. The plastic zone range of the arched roadway was calculated using three equivalent circle radius methods combined with the Fenner formula and the Drucker-Prager (D-P) criterion formula, and the Kastner approximate solution for the plastic zone boundary of the surrounding rock of a circular hole under a non-uniform stress field was obtained. The displacement, stress, and plastic zone distribution after excavation, as well as the effect of the original support, were obtained using numerical simulation. According to the plastic zone distribution of the roadway surrounding rock under the original support, the secondary support for the roof, top corners, and floor of the roadway was conducted. The results show that the equivalent circle radius method of the circumscribed rectangle and the D-P criterion are more suitable for calculating the plastic zone of the roadway in Baiyinhar mine. Combined with numerical simulation, it is found that gold-bearing altered rock is predominantly distributed in the top corners of the roadway. After conducting the secondary support, the deformation of the surrounding rock at the roof and floor was significantly reduced from the original 23 mm to approximately 8 mm and 10 mm, respectively. The stress concentration in the roof was also reduced, and the range of the plastic zone was significantly decreased, which helps to prevent shear failure of the roadway surrounding rock.