The invention discloses a gearbox low-resistance transmission and automatic lubricating oil replenishment method. The gearbox low-resistance transmission and automatic lubricating oil replenishment method includes the steps that firstly, a hydraulic push mechanism detects that gear oil in a first chamber and a second chamber is sufficient and a clutch is controlled to be in a combined state, the gear oil is normal in lubrication, and the power of an input part is transferred to an output part; then, the gear oil levels inside the first chamber and the second chamber gradually drops and are lower than the input part and the output part, the hydraulic push mechanism detects that the remain amount of the gear oil is insufficient, and the clutch is controlled to transfer the power of an inputshaft from a sliding gear to a gear oil spraying part, and the gear oil spraying part pumps the gear oil at the bottom of the second chamber upwards and sprays the gear oil to the input part and the output part from top to bottom and sprays and lubricates the input part and the output part; and finally, when the gear oil inside the first chamber and the second chamber is used up, the hydraulic push mechanism controls the clutch to switch to a separation state, and power transmission between the input shaft and a driving gear is cut off to form self-protection.