Abstract: Based on the fact that the loading of the yieldable U-steel support cannot be organically combined with the function of the surrounding rocks of roadway in complicated strata, the destabilizing mechanism was expounded in detail and the backfill technology for yieldable U-steel support was analyzed, which shows that the backfill technology behind the U-steel support can better the relationship between the support and the surrounding rock, and it can resist the partial stress concentration and fully improve the support performance. The filed application shows that the support result of backfilling behind the U-steel support is satisfactory.