As the most complex friction pair in the movement mechanism and working condition of large displacement piston pump (LDPP), the friction characteristics of the slipper pair have an important impact on the overall performance of the LDPP. Therefore, the research on the friction characteristics of slipper pair of LDPP has become a hot and difficult issue in the industry. Many experts and scholars have conducted in-depth research on the friction related characteristics of slipper pair. However, due to the test conditions, the research on the friction and wear of slipper pair mainly focuses on the torque loss and power loss caused by the friction of slipper pair of small and medium displacement piston pumps. The slipper pair of LDPP has a large area at the bottom of the slipper, so when the slipper rotates at a high speed, a linear velocity difference will be formed between the inner and outer positions of the slipper pair relative to the center of the swashplate. The cause and change rule of the friction of the slipper pair are different from those of the slipper pair of the small and medium displacement piston pump, while the generation and change rule of the friction of the slipper pair of the relevant LDPP are still lack of systematic analysis.