Abstract: Friction V-belt drive works by the friction between belt and pulley.It belongs to the application category of external friction and plays a good active force effect at the same time.On the off-road diesel engine, according to the practical analysis of engineering application, this paper focuses on its working characteristics and geometric calculation, mainly involving the origin and structural form, working composition and operation characteristics of friction belt drive, wedge supercharging principle and geometric relationship, equivalent friction coefficient and wheel groove matching, etc.