Abstract: Maraging steel (18Ni350) has excellent properties, it maintains high toughness under high strength and has strong machinability. Therefore, it is selected as the special equipment flexible connector material. The flexible connectors are made by maraging steel tubes through spinning process, solution, aging and other treatments. Spinning, as a cold deformation method, can effectively improve the utilization rate of materials. However, there are some problems such as material cracking, low elongation of finished products during the flexible connector forming process. These problems will directly affect the development process and operation of special equipment. In order to find the reason for the low elongation of products, optimize the processing route the current forming processing of flexible connectors was carried out. Samples were taken from the maraging steel tube between each process. The microstructure and properties were characterized by means of metallographic observation, tensile property test, hardness test, residual stress test and so on. The changes of the structure and properties during the spinning process were studied and analyzed. The results show that the spinning process causes the lath martensite grains to be elongated and broken, resulting in a microstructure elongated in the direction of material flow. The spinning process can obviously improve the strength of the material, but at the same time reduce the plasticity significantly. Compared with the initial state, after four passes of spinning, the tensile strength increases by 27.1%, and the elongation decreases by 55.6%. The low elongation of products is mainly caused by the deformation strengthening of spinning. Multi-pass spinning will cause the grains break, the dislocation density and residual stress of maraging steel increase, which resulting in the elongation of the products is only about 1%. After spinning, the residual stress accumulates in the material, which has an adverse effect on the subsequent deformation processing. Due to the influence of spinning processing, the microstructure refinement of the spined martensitic aging steel can be realized by solution treatment. The effect of work hardening and residual stress caused by spinning deformation can also be eliminated by solution treatment. After solution treatment, elongation and residual stress increase, tensile strength and surface hardness decrease. The microstructure after solution treatment is more suitable for subsequent plastic processing. By optimizing the process, the cracking rate of flexible connectors can decrease successfully and the elongation can increase to more than 3%.