Abstract: This paper described the effect of adding Ne or Ar on N2 laser in pulsed Townsend experiment.The restults show that released primary electrons by laser pulse striked on cathode will increase 3～6 times after adding Ne or Ar N2 laser.But the pulse duration will increase 20%～25% when adding Ne,or little change when adding Ar.So,the optimum mixed ratio of Ne and Ar to be suitable to the pulsed Townsend experiment can be experimentally fined.