Abstract: According to the problem that low strength surrounding rock of rectangular section roadway with thick top coal showed large deformation under high stress and conventional support,fractures are developed in the shoulders due to the independent anchorage body in roof and two sides which shows a loose support structure.According to the failure mechanism of roadway with thick top coal,its support prestressed field and deformation characteristics are comparatively analysed by FLAC3D numerical simulation with the support of the whole anchorage body in roof and two sides and the independent one.The results show that with the support of whole anchorage structure in roof and two sides,compressive force transfer mechanism appear and initiation and development of fractures are restrained in the surrounding rock of shoulders,the surrounding rock in roof and two sides can support each other better which enhanced theirs self-supporting capability and the nonlinear deformation like roof fall and rib spalling are prevented.Field application demonstrates that whole anchorage structure in roof and two sides achieve practical supporting effect.