With the proposal of space,deep sea,and polar region strategy in our country,the extreme operating environment and the low temperature conditions have raised higher requirements for hydraulic components and systems.In extremely low temperature environment,the fit clearances of the friction pairs in hydraulic components change with temperature,the kinematic viscosity of the hydraulic oil increases significantly,and the cold start of the hydraulic actuator is also severely affected,thereby affecting the normal operation of the entire hydraulic system.The characteristics of hydraulic components and systems in low-temperature environment were summarized,including the viscosity-temperature characteristics of hydraulic oil in low-temperature environment,friction pairs of hydraulic components,and low temperature start of hydraulic system,etc.The solutions how to anti-freeze of hydraulic system in low temperature environment were explained,such as heating and insulating oil tanks,selecting component materials with suitable thermal expansion coefficients,conducting low-temperature optimization experiments and so on.The analysis and research of hydraulic components and systems in low temperature environment has certain reference value.