A series of castor oil polyurethane-poly(methyl methacrylate) interpenetrating polymer networks (IPN COPU/PMMA) were produced from castor oil, toluene diisocyanate, and methyl methacrylate. The properties and morphology of the IPNs were estimated. The adhesives based on the IPM COPU/PMMA prepolymer were prepared and the influence of the composition on the adhesion strength was studied. The experimental results showed that the adhesives have an effective adhesive power for metals and these adhesives have good prospects in a practical project.