A series of pyrido[2,3-d]pyrimidine derivatives were synthesized by the three-component reaction of arylaldehyde, cyanoacetate, and 4-amino-2,6-dihydroxylpyrimidine in ethyl alcohol at 80 degrees C catalyzed by KF-Al2O3. It was interesting that further aromatization took place automatically. Compared with other synthetic methods, this new method has the advantage of easier workup, milder reaction conditions, and good yields.