The lubrication characteristics of the support bearings in the gearbox will greatly affect the operational performance of the gear transmission system. To discuss the lubrication characteristics of oil-jet lubricated cylindrical roller bearings under the wide speed range of power coupling mechanism, a fluid–structure coupling simulation model based on CFD method is established. The elastic fluid lubrication theory, two-phase flow VOF model of air-oil and slip mesh model are combined. The numerical simulation model of two-phase flow slip mesh hydrodynamics of the bearing under wide speed regulation range is established. The results show that with the increase of rotational speed, the local pressure in the contact area of the rolling element increases abruptly, which causes the lubrication environment of the bearing to decrease sharply. The local effect of pressure distribution in the bearing cavity slows down with the increase of ambient temperature. The overall lubricant content in the bearing cavity decreases significantly. This study may provide some guidance to improve the lubrication characteristics of cylindrical roller bearings in gearboxes.