Abstract: Through the statistical analysis of the ground pretension stress induced by rockbolt pretension obtained by numerical simulation, a practical formula was obtained by data fitting method. Rockbolting desgin for roadway of Sanyuan coalmine was conducted based on the presented formula, and a field test was carried out to verify its effectivness. The results showed that the pretension stress influence radius RP of single rockbolt or cable was positively related to its pretension force P and the negative power index of reinforced arch effect index σP. During the roadway excavation and mining of the working face, not only the axial force of rockbolt and cable but also the roof separation displacement and the surrounding rock deformation were almost the same compared to that of unoptimized roadway. And there were no events affecting the normal production of the working face. The tunneling efficiency was improved, and the investment of support materials and manpower were reduced by introducing the optimized rockbolting support. It had achieved the goal of low density support. The rationality and effectiveness of the rockbolting design by the practical theoretical formula was verified. It could provide a practical theoretical calculation method for the design of rockbolting in coal mines under similar conditions.