The influences of some materials (such as urea, melamine and inorganic clay) on the properties of PF(phenol-formaldehyde resin) adhesives were investigated by two step alkaline catalytic reaction. The results showed that the condign molar ratio of formaldehyde to phenol was 3.00:1 or 2.00:1. The urea can reduce the product cost of modified PF adhesive,but its bonding strength is decreased. The melamine can improve the bonding strength of modified PF adhesives,but its cost is increased. The inorganic clay can improve the bonding strength a...