This paper puts forward the separation and unlocking technology of line constraint for the problem of large separation impact and weak testability of traditional pyrotechnic separation device, which can not only ensure the reliable connection and separation of components, but also ensure that the impact of separation is as small as possible, reduce the impact of separation impact on the equipment load, and satisfy the complexity of the aircraft and the large load demand, by analyzing the factors affecting the winding force of the spring of the line constraint, and guiding the design of the device on By analyzing the factors affecting the winding force of the wire constrained spring, the design of the device is guided to control these factors, so that the load carrying capacity, separation impact, and other performance indicators of the separation device can meet the requirements of large load carrying, low impact, and fast separation technology. The trigger mode has an important impact on the power consumption and unlocking time of the device, and the trigger mode is selected through mechanical analysis and layout design, so that the separation device can meet the requirements of low-power consumption and fast response. The principle prototype is designed, and the feasibility and performance of the principle prototype are analyzed through simulation and experimental testing to provide comprehensive technical support for its space engineering applications.