Abstract: Squeeze effects on the lubrication behaviour of cam-tappet were investigated with a thermal elasto hydrodynamic lubrication (TEHL) simulator numerically. Comparing transient TEHL (TTEHL) simulation results with quasi-steady TEHL (QTEHL) simulation results, it is shown that the changes of film thickness, pressure, temperature and friction coefficient calculated from TTEHL model has a time lag from that of quasi-steady model. During an operating cycle of cam-tappet, only at the points with radical alteration of operating condition does the squeeze have significant effects on the tribological parameters, especially at the zero entrainment velocity points the effects are most remarkable.