The invention belongs to the technical field of solar cells, and specifically, discloses a preparation method of a crystalline silicon solar cell. According to the method, a plasma etcher used by themethod comprises a reaction chamber, an ion generation electrode is arranged in the reaction chamber; a support frame is arranged over the ion generation electrode to support a to-be-processed workpiece; an upper surface of the support frame is vertically provided with a mounting hole; a region of the ion generation electrode, corresponding to the mounting hole, is provided with a threaded hole, and the mounting hole and the threaded hole are connected through a screw; a subplate is arranged between the screw and the support frame, and the subplate can avoid loosing of the screw in the mounting hole caused by vibration; the support frame is provided with a sealing unit at the position of the mounting hole, the sealing unit is located over the subplate, and the sealing unit and the subplatecooperates with each other to realize sealing for the mounting hole of the support frame. According to the method provided by the invention, a back point contact structure technology is used for manufacturing the solar cell, cell conversion efficiency is high, and manufacturing cost is lower.