The deflagration of C2H4-O2 mixtures initiated by a single pulse from TEA CO2 laser has been investigated. It was found that the laser power threshold for initiating deflagration was a function of the laser frequency, the composition and total pressure of the gas mixture. The minimum laser power threshold was observed at the laser frequency of 947 cm-1. In the presence of Pt-Rh or Ag surface, the power threshold was obviously decreased. The main product analyzed were C2H2, CO, CO2 and H2O. Their relative quantities were dependent on total pressure and ratio of C2H4 to O2 in the gas mixtures.