Time-of-flight mass spectrum of freon 1110 (C2Cl4) under action of 400 nm femtosecond laser pulse is obtained by time-of-flight mass spectrometry technology. Three major fragment ions, C2Cl+4, C2Cl+3 and C2Cl+2 are discovered in the mass spectrum. Based on the density functional theory, the energy changes in dissociation channels of C2Cl+4 during photodissociation process are further calculated and analyzed at the basis set of B3LYP/6-311G++(d,p). The results show that C2Cl+4 needs to absorb energy during photodissociation process, which indicates that C2Cl+4 is more stable in the ozone layer. Besides, compared with the mass spectrum of C2Cl4 obtained with 800 nm femtosecond pulse laser which has been experienced by other researchers, and through calculating the proportion of each peak to total peak area and the chlorine isotope abundance ratio of major ions in the mass spectra, it is found that C2Cl4 is more likely to dissociate under infrared light radiation. Moreover, the potential energy surfaces of C2Cl4 and C2Cl+4 about C-Cl bond are scanned via the same basis set, and the saddle points are obtained. It is found that the activity of C-Cl bond of C2Cl+4 becomes higher and the C-Cl bond is easier to break than that in C2Cl4. Infrared spectrum and Raman spectrum of C2Cl+4 are calculated and analyzed, and UV-VIS spectrum is obtained with CIS method.