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The tribological properties of gear interface have been widely concerned in the past decades. In this study, based on the local involute profile and crown modification, a thermal elastohydrodynamic lubrication model is proposed for a helical gear pair. To discuss the influences of dynamic load on the tribological properties of helical gear pair, the dynamic mesh force of tooth surface is obtained by torsional vibration model. The influences of working conditions and surface roughness on the tribological properties of helical gear pair are investigated. The tribological properties are evaluated in terms of the average film thickness, friction coefficient, mechanical power loss etc. Results show that the dynamic effect of gears has a significant effect on the tribological properties, especially at a specific speed, such as resonance speed. In order to simulate gear lubrication accurately, it is recommended to adopt local involute tooth profile and consider tooth profile modification to calculate geometric clearance. The influence of input rotation speed on the dynamic characteristics and tribological properties of gear is more significant than that of input torque. The surface roughness significantly changes the distribution of interface pressure and film thickness. With the increase of roughness amplitude, the local fluctuation amplitude of pressure and film thickness increase and the dry contact occurs at the end of contact line. Meanwhile, the maximum subsurface stress moves toward the tooth surface, especial for the high frequency engineering roughness. This local stress concentration is harmful to the fatigue life of gear meshing process.