Poly(4-vinylpyridine) (P4VP)can graft onto nanosized carbon black(CB)to obtain a composite, which was quaternized and crosslinked with bromobutane and 1,4-dibromobutane to prepare resistive-type humidity sensitive material. The investigations on its humidity responses revealed that it exhibits high conductivity even at very low humidity, and both ionic and electronic conduction contributed to its conductivity. The content of CB,quaternization and crosslinking reaction of PVP greatly affect the relative contributions of the two types of conduction, thus modulating the humidity sensitive properties of the composite. Under optimized conditions, the composite exhibits a very wide sensing range of 0-98% RH.