The hydraulic air filter consists of two parts: air filter and refueling filter, which not only prevent particulate pollutants from entering the system through the fuel tank breathing port, but also prevent the mixing of particulate pollutants during refueling. Adopting copper based powder metallurgy sintered filter plates, compared with non-metallic filter materials, it has the characteristics of stable filtration accuracy, high strength, strong plasticity, convenient disassembly and cleaning, and can withstand thermal stress and impact, as well as normal operation at high temperatures.