The invention relates to a method for welding a crystalline silicon solar cell piece. The method is characterized in that a welding operator vertically places a welding strip and a solar cell piece to be welded in the front along a main grid line; the lower end of the welding strip is 3-8 mm away from the lower rim of the solar cell piece; the welding strip is kept thoroughly covering the main grid line to be welded; an electric welding iron begins the welding at a position of the welding strip, which is 3-8 mm away from the upper rim of the solar cell piece; and the electric welding iron moves downwards along the welding strip to reach a blank area at the lower end of the welding strip, which is 3-8 mm away from the lower rim of the solar cell piece. The method achieves the placement by means of 180-degree rotation based on the original welding placement, thereby preventing welding tin from accumulating on an upper electrode welding strip of a solar cell, retaining surplus welding tin on the main grid line of the cell piece in the blank area between a terminal of the upper electrode welding strip and the rim of the cell piece, extending the welding strip and reducing the stress brought by the welding tin accumulation to the cell piece.