Disclosed in the present invention is a method for preparing a thin film transistor array substrate, which comprises: preparing and forming a data line and source electrode on a base substrate, said source electrode having an annular structure; forming a first insulating layer on the base substrate; etching and forming an annular groove on the first insulating layer, the source electrode being exposed from the annular groove; preparing and forming a semiconductor active layer in the annular groove; etching and forming a recessed hole located at a region surrounded by the annular groove; preparing and forming a gate line, gate electrode and drain electrode on the first insulating layer, the gate electrode being formed in the recessed hole, and the drain electrode being connected on the semiconductor active layer; preparing and forming a second insulating layer on the first insulating layer, and etching and forming a pixel via hole in the second insulating layer; and preparing and forming a pixel electrode on the second insulating layer, said pixel electrode being connected to the drain electrode by means of the pixel via hole. Also disclosed in the present invention is a thin film transistor array substrate prepared and formed according to the described preparation method.