The remarkable optoelectronic property of all-inorganic halide perovskite nanocrystals (NCs) has inspired the exploration of these materials for a wide range of applications. However, the low conductivity of perovskite NCs thin film is regarded as the Achilles' heel, hindering further development in electronic usage. To address this issue, we employed sequential treatments of methyl acetate soft soaking and Ostwald ripening on CsPbBr3NC thin films, which improve the transport property and dramatically enhance the carrier lifetime from 11.56 to 112.5 ns. The field-effect transistor (FET) based on resulting CsPbBr3NCs thin film exhibits p-type carrier mobility of 0.023 cm2V-1s-1and ON/OFF ratio up to ∼104, which is on par with the bulk perovskite-based FETs. Furthermore, as a proof of concept, we demonstrate that the p-type CsPbBr3NCs feature high gas-sensing selectivity to detect NO2with a detection limit down to 0.4 ppm. The appealing charge-transport properties of these CsPbBr3NCs underscore their potentials for versatile applications.