With the rapid development of aerospace technology，space mechanical systems have put forward higher requirements for lubricating materials.Liquid lubricants are widely used in key components such as spacecraft bearings and gears due to their excellent lubrication performance and adaptability.However，factors such as high vacuum， high and low temperature changes，radiation，atomic oxygen and microgravity in the space environment make traditional liquid lubricants face challenges such as volatile loss， decreased thermal stability and creep during long-term service.This paper reviews the commonly used liquid lubricating materials in space，including perfluoropolyether，silicone oil，polyalkyl cyclopentane，and grease，and also focuses on new liquid lubricating materials，such as low eutectic solvents， magnetic fluids，and liquid metals.Subsequently，the influence mechanism of the space environment on liquid lubricants is analyzed，and future development trends are discussed，including near-zero friction and wear，self-adaptation，solid-liquid composite，and intelligent lubrication systems.Finally， optimization strategies and characterization methods for space liquid lubricating materials are proposed to provide theoretical guidance for designing spacecraft lubrication systems.