An organic thin film transistor, a preparing method thereof, and a preparation equipment. The preparation equipment of an organic thin film transistor comprises: forming a gate electrode, a gate insulating layer, an organic semiconductor layer, and source-drain electrodes on a substrate; the step of forming the organic semiconductor layer comprises: blade-coating a solution in which an organic semiconductor material used to forming the organic semiconductor layer is dissolved to form the organic semiconductor layer. The preparing method can avoid the difference between the edge and the center of the substrate caused by the impact of centripetal force when a spin-coating method is applied, so that the yield of the organic thin film transistor devices is improved.