Proton conduction of polyoxometalate has been received considerable interest because of their unique structural properties. The fabrication of hybrid polymer films of polypyrrole–polyoxometalate was reported with their resistive-type humidity sensing performance. The hybrid polymer nano films with different thickness were elaborately prepared via co-electrodeposition of free pyrrole monomers with metal oxide clusters. The sensing response/recovery time of sample with the thickness of 59 nm exhibited 1.9 s and 1.1 s at 98% relatively humidity and the sensing range is 11%~98% relatively humidity. In polypyrrole chain, the outstanding sensing could be ascribed synergistic effect of the proton acid doping structure and the oxidation doping structure. The humidity sensor based on nanocomposite was found to be repeatable even after two months remaining well-operated response and recovery time.