Post isothermal treatment was effectively used to improve not only the internal bonding strength, but also its property homogeneity of the particleboard with low molar ratio and non dewatering urea formaldehyde resin with or without curing agent added. During the thermal treatment the curing agent didn’t cause any degradation of adhesives. The post isothermal treatment conditions were suggested as keeping panels in an oven at 80 ℃ for 30 minutes while the center temperature of panels after hot pressing was cooled to 100 ℃.