Abstract: The micro-thermal elastohydrodynamic lubrication of an eccentric-tappet pair was investigated by assuming a harmonic waviness on the flat-tappet surface. The effects of wavelength and eccentricity of the eccentric were explored. The calculation results show that the surface waviness can cause fluctuations in pressure, film thickness and temperature profiles. The amplitude deformation of the surface waviness varied with the slide-roll ratio. During the half period with opposite motion, the slide-roll ratio increased with the eccentricities, causing the reduction in the amplitude deformation. The elastic deformation of the waviness in opposite motion was controlled by the "temperature-viscosity wedge" effect.