Oil returning system capable of automatically controlling hydraulic oil temperature used for excavator

The invention discloses an oil returning system capable of automatically controlling a hydraulic oil temperature used for an excavator. The system comprises a power source and an oil feed pump connected with the power source, wherein the outlet of the oil feed pump is respectively connected with a main control valve and a control oil pump; the outlet of the main control valve is connected with a radiator through a first back pressure valve; and the outlet of the radiator is connected with a hydraulic oil tank. The system is characterized in that: the outlet of the main control valve is also connected with a second back pressure valve; the second back pressure valve is a controllable back pressure valve; the outlet of the second back pressure valve is connected with the hydraulic oil tank; and the control oil port of the second back pressure valve is connected with a temperature control module. In the system, by connecting the second back pressure valve at the outlet of the main control valve and controlling the on-off state of the second back pressure valve by the temperature control module, the hydraulic oil reaches an ideal working temperature so as to ensure that the influence of the hydraulic oil caused by an environmental temperature is minimal.