Aiming at the locale facts of difficult roof controlling for large span gateway of fully-mechanized coal faces, based on analysis of the influence factors of monolayer strata stability, the numerical simulation soft UDEC3.0 is employed to deeply research influence factors and changing rules of roof stability of the gateway which is composed by some monolayer strata. A new supporting idea of reducing span supporting function by bolts cooperating with anchor cables is brought forward by disposing anchor cables at the appropriate locations, the traditional supporting theory such as suspensory and compounding beam (arch) are still operated at the same time. A good result is achieved after the new supporting idea is applied in the large span gateway of Bulianta Colliery in Shendong diggings.