Abstract: Stability relationship between hydraulic support and surrounding rock is one of the important and difficult contents in the research of longwall mining and its intelligence. The occurrence conditions of steeply-dipping coal seams are complicated, and it is difficult to control the stability of “support-surrounding rock”. It seriously restricts the safe and intelligent mining of this kind of complex and difficult coal seam mine. Therefore, a 3D large-scale simulation experiment platform and hydraulic supports are developed in the laboratory environment, which can simulate the in-situ environment of the steeply dipping coal seam. It can simulate the coupling control of working face support and surrounding rock system, the effect of roof periodic pressure and rock burst. Based on digital twin technology, the twinning system of “support-surrounding rock” experimental platform was constructed. It can realize the accurate perception and efficient simulation of the “support-surrounding rock” system of the physical space simulation experiment. A series of simulation tests were carried out, such as the performance of the experimental platform, the research and development of the special-shaped hydraulic support, and the optimization of the twinning system of the “support-surrounding rock” experimental platform. The stability of the whole structure and the reliability of the performance of the three-dimensional large-scale simulation experiment platform were determined, and the practicability and accuracy of the twin system were also determined. Test results indicated that during roof weighting periods, hydraulic supports were prone to lateral deflection instability under dip angle effects, with inter-support lateral compression intensifying. The integrated “support-surrounding rock” system comprising roof strata, supports, coal walls, and floor strata functions as a coordinated load-bearing structure, where variations in any component compromise overall stability and thereby exacerbate failures in other constituent elements. To enhance the stability of the “support - surrounding rock” system in working faces with complex coal seams, three improvement measures are proposed: implementing anti-toppling and anti-sliding devices for hydraulic supports, strengthening the control of surrounding rock, and conducting real-time monitoring and early warning.