During low mole weight PF resin composed with fire retardant FRDL 112 or H 3BO 3 modified Poplar( Populus ussuriensis ) wood, the liquid added FRDL 112 impregnates wood much easier than that added H 3BO 3 does. H 3BO 3 influents on the anti swelling or shrinkage and moisture excluding properties of PF modified wood worse than FRDL 112 does. The addition of FRDL 112 weakens the compressive strength parallel to grain and hardness of PF modified wood, but the properties are still stronger than those of untreated wood. According to the result of fire retard experiment, FRDL 112 is much better than H 3BO 3. The addition of FRDL 112 influents badly on the antiseptic property of modified wood with PF resin. The antiseptic property of modified wood with PF resin and H 3BO 3 is better than that of modified wood with PF resin but H 3BO 3 is leachable.