Abstract: In order to deeply comprehend the wear regularity of chilled alloy cast iron tappet,the influence of surface layer microstructure on wear resistance was studied.When the microstructure of surface layer is in the form of fine spot graphite and acicular or blocky carbide distributing equably,wear resistance of the tappet is high and wearing form is mainly scratch and pitting corrosion.Otherwise,when the microstructure of surface layer is in the form of lamellar graphite and rough acicular or blocky carbide distributing unevenly,wear resistance of the tappet is low and wearing form is mainly spalling corrosion.