The purpose of this study is to determine the influencing factors and changing laws of the friction behavior of a wet clutch under actual working conditions. A qualitative analysis is conducted on the torque characteristics of a wet clutch and influence laws such as the relative and absolute speeds of the driving and driven ends of the clutch, lubricant flow, engagement force and its change rate, lubricant temperature, and friction surface temperature. The identified influence mechanisms and friction behavior can be used for the design and production of a precise controller for the transmission torque of a wet clutch. •Analysis of a wet clutch was performed under actual working conditions.•Precise design of controller was explored for transmission torque of wet clutch.•Influencing factors and changing laws of friction behavior were explored.•Relative and absolute speeds of driving and driven ends of a clutch were determined.