The invention discloses a front end wheel train structure for an off-road diesel engine. The front end wheel train structure comprises a water pump cushion plate, a water pump driving wheel, a fan driving wheel, an automatic tensioning wheel, a crankshaft shock absorber driving wheel, a power generator driving wheel, an idle wheel and a transmission belt, wherein the water pump cushion plate is installed on a cylinder body and a cylinder cover through bolts, and an air conditioner is installed on the water pump cushion plate through an air conditioner adjusting support; the water pump driving wheel is arranged on a water pump which is fixed to the water pump cushion plate; the fan driving wheel is arranged on a fan, and the fan and the water pump are separately arranged on the water pump cushion plate through a fan support; the automatic tensioning wheel is fixed to a water pump cushion block; and the transmission belt is sequentially wound around the crankshaft shock absorber driving wheel, the water pump driving wheel, the fan driving wheel, the automatic tensioning wheel, the power generator driving wheel and the idle wheel. By means of the front end wheel train structure, the water pump and the fan are arranged separately, the speed ratio of the water pump, the fan, an air conditioner and a power generator is adjustable, suitability is good, the position of the fan is adjustable, and the requirements of a harvester, a forklift, a tractor and other market segments are met.