In order to study the mechanism of roof separation inside and outside the anchorage area of soft rock roadway,Taking the air return roadway of 50213 working face in Guantun Coal Mine as the engineering background, based on the principle of superposition method, the mechanical model of the inner and outer roof separation of the anchor cable anchoring area of the soft rock roadway is established. The calculation formula is used to analyze the influence law of the amount of roof separation inside and outside the anchor cable anchoring area, and the influence degree of each factor is determined. Through similar simulation, the evolution law and reason of the separation of the roof inside and outside the anchoring area of the anchor cable are analyzed, and the "inverted trapezoidal" support technology of high pretension long cable is proposed, and the control effect of surrounding rock is carried out by numerical model. The simulation results show that the plastic zone of surrounding rock is significantly reduced after optimization, the maximum subsidence of the roof is reduced by 50.7% compared with the original plan; The problem of roof separation ensures the stability of the surrounding rock of the roadway.