Abstract: This paper is mainly to study the subsidiary shaft's stability which may be potentially deformation failure owing to the varying engineering geologic condition in depth. With the help of the adjacent main shaft's engineering geologic condition the relation between the liner's thickness and releasing deformation is probed by using numerical analyses. The research shows that the rational thickness of liner of the subsidiary shaft is about 700mm and rational releasing displacement is 70～90mm. In order to satisfy safely using space the diameter of the shaft would increase up 6.35m from designed 6.3m. The revised design proposal had been adopted and obtained success in the construction of the shaft.