Aiming at studying the key factors of roof stability of double-side mining roadway in the superposition stress area in hecaogou coal mine，comprehensive research methods such as field measurement, numerical simulation, laboratory experiment and theoretical analysis were used, the key factors which are "key stratum", "key position" and "key location" were obtained. Based on the core factors affecting the stability of the roadway, this paper also proposes a targeted support scheme, which effectively controls the malignant expansion of the plastic zone and maintains the stability of the roadway. The results show that there are four kinds of aluminum-clay mudstone enrichment areas in the roof of the roadway. Moreover, after detailed analysis of the distribution location of the weak interlayer, it is found that the interlayer mainly exists at the position of 0-3m above the roadway, and the range of roof 0~3m is the "key stratum" controlled by the roof of the roadway. During the transition period from the influence of unilateral mining to the influence of bilateral mining, the plastic zone gradually expanded from the two corners of the roof, and the two corners of the roof were the "key position" to control the malignant expansion of the plastic zone in the roadway. From the law of axial development of the plastic zone along the roadway, the "key location" which controls the stability of the roadway surrounding rock is obtained. A spatial trinity key control technology system is put forward, and a control scheme is given. The control effect is good, which effectively prevents the slagging of the large concrete from hurting people and eliminates the hidden danger of the roof.