Based on 1-D fluid Model, numerical simulation was adopted to study the effect of small admixtures of oxygen on the characteristics of argon and oxygen mixture discharge at atmospheric pressure. According to the model equations, the simulation results showed that as the ratio of oxygen to argon increased from 0.1% to 0.6%, the electron density decreased, the density of O? increased, the density of the total negative particles increased, the electron temperature in sheath decreased. Furthermore, with the increase of discharge time, the density of O? increased, the electron density was obviously divided into three stages: the stage of electron growth, the stage of electron reduction and the stage of electron unchanged. When the ratio of oxygen to argon was within the scope of 1%, the electron density decreased rapidly, the oxygen atom density increased quickly. However, when the ratio of oxygen to argon was between 1% and 4%, as the ration of oxygen to argon increased the electron density decreased slowly and the oxygen atom density grew slowly until held the line.
