The broad bean (Vicia faba L.) seeds were irradiated by He-Ne laser and CO 2 laser, then both of MDA and AsA were tested in the stage of their seedlings. The results showed that He-Ne laser was better that CO 2 laser. The best dose of He-Ne laser was 5.43 mW·mm -2 . He-Ne laser pretreated seeds and 3.03 kJ·m -2 UV-B irradiated seedlings in the condition of PAR 70 μmol·m -2 ·s -1 . SOD, POD, CAT enzyme activity, SOD, POD, CAT isoenzymes were measured. The results showed that He-Ne laser could enhance SOD, POD, CAT enzyme activity, changed SOD, CAT isoenzyme bands. It was concluded that laser pretreatment could protect broad bean seedling from UV-B irradiation damage.