The stability control of roadside support body is the key to keep gob-side entry retaining stable. According to the structural mechanics model of gob-side entry retaining overlying strata

the paper analyzes the load and deformation characteristics of roadside support in the three stages and obtains supporting mechanism of roadside support as follows. Roadside support body could support the roof instantly by increasing support resistance in the setting stage

meets the requirement of cutting off a certain height of the roof before a periodic abutment loading at the back of working face

and has a large deformation capacity during overlying strata movement and a high post-strength after stability of overlying strata movement. Based on the above investigations and the geological conditions of panel 24021 in Jiulishan colliery

we analyze the effect of support body width on the performance of a gob-side entry retaining

and determine a rational width of support body in the condition of support parameters and filling materials. Research results are successfully applied to a field practice.