In this paper, actinometric optical emission spectroscopy (AOES) is used to inve stigate the discharge of CF44 and CH44 mixtures. Relat ive concentratio ns of radicals in an inductively_coupled plasma are determined as functions of rf input power, pressure and the gas flow ratio R (R=［CH44］/［CH 44］+［CF44］). It is found that CF，CF22 ，CH，H and F radicals exis t in the CF44/CH44 plasma as well as C22 radical. The relative co ncentration of C22 increases with increasing power, and shows a rev erse “U” shape tendency with increasing pressure. As R increases, the variati on of the relative concentration of C22 is not monotonical. It reac hes a ma ximum value when Ｒ＝75%, then decreases followed by almost no change with the further increase of R. Based on these results, it is concluded that gas_pha se reaction from the reaction of CF and CH （ＣＦ＋ＣＨ→Ｃ２2＋ＨＦ ） contribu tes to the production of C22 radical. At the same time, activation reaction model of radical collision is suggested. Result of simulation agrees well with that of experiment.