A preparation method of an oxide thin-film transistor is disclosed, and this method includes: forming a gate electrode, a gate insulating layer, an active layer, a source electrode and a drain electrode; forming of the active layer, the source electrode and the drain electrode includes: sequentially forming an oxide semiconductor thin film and a source-drain electrode metal thin film on a base substrate, an entire surface of the oxide semiconductor thin film being in direct contact with the source-drain electrode metal thin film; and patterning the oxide semiconductor thin film and the source-drain electrode metal thin film with a dual-tone mask so as to form the active layer, the source electrode and the drain electrode by a single patterning process.