Abstract: The article discussed the best activation standard of ductile iron, 45# carbon steel and 40 chromium alloy, adopting the quadratics rotary orthogonal combination experiment design method, taking activation current density and time as two factors when the other circumstance was stable. By analyzing the rule that the activation current density and time influence the adhesion strength, the differences of the best activation standard among the three materials were pointed out. The mechanism of activation was analyzed based on the metalgrophic test and scaning electronmicrograph.