Abstract：Mechanism of some serions rock caving cases in rock bolted coal roadway is very complex. There are mainly two reasons：the one is the uncertainty of physical parameters and mechanical characteristics of surrounding-rock，and the other is that various calculation models used for analyzing the stability of surrounding-rock in roadway only partly reflect the mechanical behaviors of surrounding-rock. To improve design approach based on safety coefficient and to consider stochastic factors as mentioned above，based on a model of loose weight for rock-mass of underground pressure theory and a principle of resistance force development in structure supported by rock-bolt，the paper researched calculation methods of resistance force and load in limite state equation which was used to calculated stability degree of surrounding-rock in coal supported by rock-bolt. A stability reliability degree for surrounding-rock of a underground roadway in coal supported by rock-bolt has been calculated，and the conclusion is that failure probability about l0 percent of surrounding-rock in a rock-bolt supported coal roadway is acceptable.
