Nylon 66 thin films were prepared by layer-by-layer polycondensation. Two kinds of bifunctional monomers were deposited alternatively onto the substrate. The films showed the highly ordered structure with the molecular orientation normal to the substrate. It was found that the thickness and the molecular weight of the nylon 66 film could be effectively controlled by the number of deposition reaction cycle. The molecular weight of the film was proportional to the him thickness.