The principle of earthquake is to absorb the vibration energy and shock wave brought by the vibration of the electric vehicle through the damping characteristic of the hydraulic oil, and then it is converted into warm evaporation. Therefore, the quality of hydraulic oil, how the viscosity directly related to the size of the damping force provided, related to the shock absorber damping effect. Therefore, we must make the following requirements for hydraulic oil. 1. The oil vaporization of the electric shock absorber hydraulic is as small as possible. When the electric vehicle is running, the hydraulic oil evaporates with the increase of temperature, and the vaporized small hydraulic oil makes the service life longer, the shock absorption effect is good, and the various use environments are met at the same time. ,Use a wide range. 2. The hydraulic fluid of the shock absorber of the electric vehicle has a low freezing point, and the lower freezing point can make the electric vehicle run normally in a cold climate in the north, generally requiring a temperature below -40 degrees Celsius. At the same time, it has a good viscosity index and viscosity-temperature performance. 3. Shock absorption oil cleanliness, clean hydraulic oil can reduce shock absorber wear, ensure shock absorption, increase its service life 4. The anti-friction oil must have anti-rust and anti-wear effects to protect the shock absorber from rust and wear damage. 5. The shock absorber oil must have good working stability, anti-oil-gas mixture stability and oxidation stability.