Abstract: The friction and wear properties of SDC81 cold working die steel after vacuum heat treatment under 20, 50 and 100 N loads for different time were studied at room temperature. At the same time, the friction and wear properties of dry friction and oil lubrication were compared under the extreme conditions of 100 N for 2 h. Friction tester was used to carry out the test, and the optical profiler, optical microscope(OM), scanning electron microscope(SEM) and energy dispersive spectrometer (EDS) were used to analyze the wear volume, wear rate, microstructure and different wear scar morphologies. The results show that the wear mechanisms in the test include abrasive wear, adhesive wear and oxidative wear. Due to the increase of load and time, the wear mechanisms from abrasive wear to abrasive wear and slight adhesive wear are finally severe adhesive wear, abrasive wear and oxidative wear. Abrasive wear exists in the friction process under different loads. With the increase of load and time, the oxidation intensifies and the effect of oxidation wear mechanism becomes larger. The wear volume increases with the increase of load and time, and the wear rate decreases with the increase of load and time. The oxidation wear mechanism plays a key role in reducing the wear rate. Compared with dry friction, the relative sliding distance of oil lubrication at 100 N for 2 h is significantly reduced, and the wear rate is greatly reduced. The wear volume is about 1% of the dry friction, which plays a good lubrication effect.