In order to fabricate intact and precise ceramic microcomponents applied in microelectromechanical systems (MEMS), thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) brushes are grafted onto poly(dimethylsiloxane) (PDMS) micromolds by visible light-induced polymerization. The application of PDMS-Br@PNIPAAm micromolds in soft lithographic fabrication of ceramic microcomponents is demonstrated by producing alumina green microcomponents. The PDMS-Br@PNIPAAm micromolds are hydrophobic with a water contact angle of 129.7 ± 0.3° at 15 °C. During the molding process, the micromolds are changed to hydrophilic with a water contact angle of 81.3 ± 0.4° at 4 °C, which could improve the flowability of aqueous alumina slurry by forming intermolecular hydrogen bonding with PNIPAAm chains. During the demolding process, the micromolds are hydrophobic as the intermolecular hydrogen bonding is broken after drying. Consequently, free-standing alumina green microcomponents with microchannels of 73.7 ± 0.8 μm wide are fabricated by microtransfer molding, a maximum aspect ratio of 3.6 could be achieved. The lateral and longitudinal shrinkages of the microchannels are 9.8 ± 0.6% and 11.5 ± 0.4% respectively. The PDMS-Br@PNIPAAm micromolds can be reused more than 13 times. It is believed that moisture-sensitive PDMS-Br@PNIPAAm micromolds can be effectively used to fabricate ceramic microcomponents with high aspect ratios for MEMS.