Abstract: A kind of coating used in the pretreatment coating of CO2 laser surface modification is studied.The thermal penetration depth,hardness and surface coarseness of the hardened layer have been examined with the coating used in laser surface hardening treatment.The experiment results indicate that the coating is of merits because it has high absorption rate,high conductivity and good thermochemical stability.The coating has no erosion,poison,pollution and sputtering.It is low-cost,harmless,and easy to remove.It completely meets the demand of laser hardening.