The high pressure LOX supply system is the important sub-system in the extruding li- quid rocket engine test stand and is the highest pressure gas-pressurized feed system in China. Some problems existing in the design of high-pressure low-temperature propulsive agent pipelines were solved through the rational pipeline arrangement, design of special supports, self compensation and pile-up heat insulation technology. This system was proved to be reliable after several times of hot fire tests and can meet the design requirements.