Abstract: Being a catalyst,gold sited directly in capillary of sealed-off CO2 laser can make CO2 effectively recompose that disassociated with the discharge,but cause change of the performance status of device yet.This paper investigated the electric field distribution,available volume of plasma and exciting efficiency,drift current,ambipolar diffusion,the neutralization of the charges on the wall in capillary,especially the wall-current,performed further contrasting test with ring film and separate film plated by means of the plating technology ourselvse and non-catalyst devices,founded their mathematical model and made program to simulate numerally,pointed out that the conducting ring film result in the efficiency decline and change or going so far as to worsen the characteristic of laser performance,definitely advanced the new concepts and relevant device design about separate and disperse film catalyst and confirmed their superiority,and,modified the conclusion of previous work,i.e.,both the breakdown voltage and the terminal voltage were increasing in the gold-ring tube.