The intensity dependence of two-color laser single resonance UV photon ionization of gag phase CS2 and the features of resonance ionization of higher excibedstate (1∏g) are presented in this paper.The experiment shows that the total ionization cross-section of three-photon ionization with two-photon resonance excitation via the intermediate state, 1∏g, is higher than that with one-photon resonance excitation via the lower state, a-3A2.The saturation effect was observed under the laser intensity of 107W/cm2. The results indicate that by measuring the intensity dependence of two-color laser single resonance ionization, a new method for speotrosoopio analysis was deveilopsi. This would be signifioan b in the study of molecular structure at high excited state.