The optimal mixing condition of four components gas(Ne,Xe,He,Ar) in PDPs was caculated by a numerical simulation method. The dominated reactions in which $Xe^*(^3P_1)$ is produced and decays were investigated in three components gas (Ne,Xe,He) and our new components gas (Ne,Xe,He,Ar). A peak point of $Xe^*$ density appears in the range of 0.1% to 2% of Ar mixture ratio. The results of simulation show that the direct exitation of Xe by electrons has the greatest influence on the inceasing $Xe^*$ density in both gas mixtures.