The working principle and design characteristics of electricalhydraulic stepping cylinder were introduced. The mathematical model of the oil cylinder was established, and the simulation model of the hydraulic system was established by using AMESim simulation software. The effects of different covering amounts, different sharpedged fillets, and different valve port shapes on the overall system performance of the threeway valve were studied. The results show that the covering amount of the valve has a greater impact on the positioning accuracy of small displacements; the radius of the sharp edges of the spool’〖KG-*2〗s working edge has an impact on the performance of the spool valve, which will affect the flow characteristic curve of the small opening area, but the impact is limited. The rectangular and trapezoidal orifices have a constant rate of change in the area of overcurrent, they have good adjustment performance, and are more suitable for working in high temperature environments. The research results provide guidance for the engineering practice of the hydraulic cylinder and provide theoretical basis for further optimization of the system.