In this paper, the 431301 working face of Liangshuijing Coal Mine in Yulin, Shaanxi Province is taken as the engineering background. Based on the failure mode of roof surrounding rock in the process of working face mining, the characteristics of roof movement are divided into four stages. The mechanical model of space-time evolution of roadside support body in gob-side entry retaining at different stages is constructed respectively. The expression of lateral load applied by roof movement to roadside support body in different stages is calculated, and the coupling relationship between roof influencing factors and lateral load of support body is determined. The results show that the lateral load degree of the roadside support body is inversely proportional to the thickness of the immediate roof and proportional to the bending rotation angle of the rock beam. At the same time, the load is mainly affected by the length of the ' cantilever beam ' of the basic roof. Aiming at the roof movement characteristics of gob-side entry retaining and the lateral loading mechanism of roadside support body, the load reduction control scheme of roadside support body of gob-side entry retaining is proposed.