Abstract: Numerical simulation is an effective tool to study the internal jet characteristics of plasma DC arc due to its low cost. In this paper, the jet characteristics of plasma generators under different gas conditions are studied by numerical simulation. The results show that the temperature distribution and velocity distribution in the laminar plasma have a great relationship with the physical properties of the working gas. Under the condition of 75 A current and 3 g/s flow rate, the argon temperature is the highest and the hydrogen temperature is the lowest in the arc chamber. In most areas outside the anode, the temperature of oxygen is the highest, followed by nitrogen and then argon. The arc is not fully formed in nitrogen and hydrogen. The temperature distribution of several gases is U-shaped in the arc chamber, and the axis velocity increases in the arc chamber and decreases outside the arc. In this paper, the jet characteristics of DC arc plasma are analyzed from the point of view of gas physical property parameters, which provides crucial guidance for the research of DC arc plasma generators and their practical application in different scenarios.