The present invention a manufacturing method of a TFT (Thin Film Transistor) substrate and a TFT substrate. The method comprises: a first insulation layer and an insulation film are continuously deposited in order on the bottom layer of a conducting layer, after an interlayer function layer is formed on the insulation film, a second insulation layer is formed on the insulation film, the insulation film is the same as the second insulation layer in film quality and crystal structure, when the second insulation layer, the insulation film and the first insulation layer are subjected to dry etching to form a via hole penetrating the second insulation layer, the insulation film and the first insulation layer, the interface between the side walls of the via hole in the film layer cannot have etching chamfering so as to avoid fracture of the top layer of a conducting layer deposited in the via hole, ensure the circuit stability of the TFT substrate and improve the reliability of the TFT substrate.