The invention provides a semiconductor oxide thin film, a preparation method thereof and a thin film transistor comprising the semiconductor oxide thin film. The preparation method comprises the following steps: (1) mixing a precursor of a semiconductor oxide MO, a stabilizer, an amine additive and a solvent, and performing standing and aging to obtain a precursor solution; (2) coating a substratewith the precursor solution obtained at the step (1), and performing annealing to obtain the semiconductor oxide film, wherein the amine additive is selected from one or a combination of at least twoof primary amines with the carbon atom number less than or equal to 3. By adding the amine additive with small steric hindrance into the precursor solution, the removal of alkoxy in a metal alkoxy compound and the generation of metal oxide in the process of preparing the semiconductor oxide thin film by a solution method are promoted, and the thermal stability of the semiconductor oxide thin filmand the bias thermal stability of the thin film transistor are improved.