Abstract: The present invention discloses a thin film solar cell and manufacturing method thereof. The thin film solar cell comprises a substrate, a first electrode layer, a photoelectric conversion layer and a second electrode layer. The first electrode layer is formed with a plurality of first grooves so as to divide the first electrode layer into a plurality of unit cells. The photoelectric conversion layer is formed with a plurality of third grooves. A first offset exists between each third groove and each first groove. The second electrode layer is formed with a plurality of second grooves extending downward adequately into the photoelectric conversion layer. A second offset exists between each second groove and each third groove. The thin film solar cell further comprises at least one isolation groove positioned around the second electrode layer; out of projections of the unit cells, and extended downward so as to remove the second electrode layer.