According to the meshing characteristics of double involute gear profile,a mixed elastohydrodynamic lubrication model was established based on loadsharing and elastohydrodynamic lubrication theory.The difference of lubrication and meshing characteristics between double involute gears and involute gears with the same parameters was analyzed by contrast method,and the effects of design parameters on lubrication characteristics were investigated.The results show that lubrication and meshing characteristics of double involute gears are different from those of ordinary involute gears due to the effect of tooth waist order.Under the steadystate load,the lubrication performance of the double involute gear is better than that of the ordinary involute gear except that the contact line is all located in the meshing area of the tooth top.The central film thickness is decreased with the increase of the tooth waist altitude coefficient,and the friction coefficient is increased with the increase of tooth waist altitude coefficient.The central film thickness is decreased with the increase of the tooth waist tangential modification coefficient at the tooth top,whereas the changing rule of the central film thickness at the tooth root is opposite to that in the tooth top.The friction coefficient is decreased with the increase of the tooth waist tangential modification coefficient.