The invention particularly relates to a special tool set for assembling a spring energy accumulation sealing ring and an assembling method, and the special tool set and the assembling method are used for assembling a certain type of steering engine. The spring energy accumulation sealing ring is commonly only used for a sealing groove of an open type structure. Due to the limitation from a space structure, a sealing groove of a certain type of steering engine can only adopt a closed structure, and no effective assembling experience can be used by the structure for reference at present. The special tool set for assembling the spring energy accumulation sealing ring and the assembling method are provided. The special tool set comprises a U-shaped dismounting and mounting tool, a hemisphere shaping tool, a Z-shaped shaping tool and an auxiliary bearing ring. A sealing body and an elastic body are separably assembled, and the spring energy accumulation sealing ring is assembled in the closed structure. Accordingly, the assembling efficiency is improved, and the assembling quality is guaranteed. The application prospect is wide. The operation method is simple and reliable, and practicability is high. The assembling tool set is reasonable and scientific in design, and the assembling quality is guaranteed.