Abstract: The laser-pulsed MAG hybrid welding system and acquisition system were set up to get the electric signal and arc spectrum under the conditions with and without laser. To analyze the relationship between arc energy input and the spectral radiation intensity of FeII274.648, FeI382.043, FeI492.050 and ArI801.479 using the method of linear fit. Studies have shown that the spectral radiation intensity of the four feature spectrum lines are proportion to arc energy input. With the same arc energy input, the arc radiation intensity of hybrid welding is smaller than the one of pulsed MAG welding. This is because the metal vapor and plasma produced by laser may absorb the arc plasma radiation.