A numerical simulation method of DC plasma torch is described in this paper.The temperature

velocity

currency density distribution on different boundarycondition of plasma torch are obtained by resolving the energy

momentum

massconservation equations of arc column. The temperature

potential

currencydistribution of the atmosphere were calculated

200A free burning argon arc and theresults are consistent with the experiment data and other theoretical results. On thebasis of this

the numerical simulation in the arc column of the 5000A high powerplasma torch with the presence of cathode nozzle was discussed. The influence of theradiation factor

Joule heating factor in the energy conservation equation wereconsidered also. The relation between the maximum temperature and the length ofarc is also discussed.