The 1+1 two-photon resonant enhanced multiphoton ionization spectra of chlorobenzene were obtained at the range of 262～272 nm on the laser mass spectrometer with heatable sample inlet system which was designed by ourselves. The result shows that the structure of the excitation spectra in this wavelength range represents the first excited state 1B2(S1) of the chlorobenzene. 14 spectrum lines were assigned. The characteristics of the photon ionization mass spectrum at 266 nm were analyzed. The non-symmetric broadening of the mass spectrometry of the 77C6H+5 was analyzed. The relationship between the signal intensity of chlorobenzene and the sample concentration was studied. It is shown that the detection limit of the chlorobenzene is about ng/L range.