In order to determine the rational width of backfill in the goaf-side retained roadway, the deformation failure mechanism of surrounding rock in retained roadway is studied in the use of theoretical analysis, numerical simulation, etc., when the width of backfill is different. The results show that: with the increase of backfill width, the roof deformation above the backfill decreases; the outside of backfill obviously suffers from greater stress compared to the inner side of backfill; the damage firstly appears in the intersection of top backfill and roof; the plastic failure area is mainly distributed in the roof and floor of inside the roadway; 2 m wide backfill in the goaf-side retained roadway can meet the requirements of roadway deformation. Based on the original combination support of “anchor-mesh-belt-lock” in the haulage-track roadway, the study also considers the reinforced support of “anchor-mesh-belt” above the backfill, and 50 m ahead of working face, and 200 m behind the working face. This kind of support achieves a good result. The roadway deformation of field measurement shows that it can satisfy the need of the next working face. In order to determine the rational width of backfill in the goaf-side retained roadway, the deformation failure mechanism of surrounding rock in retained roadway is studied in the use of theoretical analysis, numerical simulation, etc., when the width of backfill is different. The results show that: with the increase of backfill width, the roof deformation above the back fill decrease; the outside of backfill obviously suffers from greater stress compared to the inner side of backfill; the damage first appears in the intersection of top backfill and roof; the plastic failure area is mainly distributed in the roof and floor of the roadway; 2 m wide backfill in the goaf-side retained roadway can meet the requirements of roadway deformation. Based on the original combination support of “anchor-mesh-belt -lock ”in the haulage-track roadway, the study also considers the reinforced support of “ anchor-mesh-belt ”above the backfill, and 50 m ahead of the working face, and 200 m behind This working face. This kind of support achieve a good result. The roadway deformation of field measurement shows that it can satisfy the need of the next working face.