||To make capacitive type relative humidity sensor, we prepared polyimide/polyurethane blends and polyimide-polyurethane block copolymers containing various ratios of polyimide/polyurethane from 4, 4’-diaminodiphenyl ether(ODA)/pyromellitic dianhydride(PMDA)/poly(tetrametylene oxide) glycol(PTMG)/4, 4’-dicyclohexylmethane diisocyanate(H12MDI)/ethylene diamine(EDA). The chemical structure of blends and copolymers was identified using FT-IR. This study focused on the effect of polyimide/polyurethane ratio of blends and copolymers on the capacity, mechenical properties and thermal properties was investigated. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea Government(MSIP) through GCRC-SOP (No. 2011-0030013).