Abstract: A large range of caving roof of gob-side entry retaining is easy to cause impact damage of the roadside backfill body. In order to ensure the stability of gob-side entry retaining, different from the traditional large-angle inclined roof cutting method, a controlled roof cutting method is proposed to reduce the lateral impact damage of roof caving to the roadside backfill body by controlling the roof caving thickness from the source. Based on the background of goaf retaining in the 150110 fully mechanized caving of Pingan Mine in Shouyang, Shanxi Province, a grouped caving mechanical model was established, the expressions of flexural deformation and interaction force of the upper and lower strata were analyzed, and the internal process of the lower strata breaking and caving under the pressure of the upper strata and its own gravity after the thick hard roof was stratified was clarified. The mechanism of group caving of thick hard roof is revealed. According to the four processes of roof caving movement, roof breaking and turning, roof and goaf gangue collision, goaf gangue compaction and energy absorption, gangue compaction and side impact on roadway. Aiming at the process of lateral impact load on the side backfill after gangue compaction, a mechanical model of roof caving impact is established, and the expression of lateral impact load on the roadside backfill body is derived based on displacement variational method. The effects of layer thickness and strength of thick hard roof, thickness of direct roof and lithology on lateral impact load are analyzed. The relationship of influence degree of each factor is obtained by combining sensitivity analysis. It is verified by UDEC numerical simulation that group controlled cutting roof can reduce the impact damage of roof caving on roadside backfill body. The results show that: the higher the layer thickness of thick hard roof, the higher the lateral impact load; The lateral impact load of the thick hard roof gradually decreases as the layer thickness and caving height decrease, and the lateral action tends to the static load state; The impact load of the roadside backfill body is mainly in the middle and lower part. With the increase of the thickness of the immediate roof, the impact load of the roadside backfill body gradually decreases and is evenly distributed. The change of the strength of the thick hard roof (that is, the change of the caving length of the thick hard roof) has little influence on the lateral impact load caused by the layered caving, and the lateral impact load increases gradually with the increase of the strength of the roof. The lateral impact load is negatively correlated with the crushing coefficient of the immediate roof K_p, and positively correlated with the elastic modulus E and Poisson’s ratio μ, and decrease with the increase of the immediate roof strength. In engineering application, the layering thickness of the low thick hard roof should be reduced as much as possible, and the layering thickness of the high thick hard roof should be increased appropriately to reduce the amount of cutting the top.