The invention belongs to the technical field of a wind driven generator, and relates to a large-sized direct-driven wind driven generator, in particular to a lamination tool and method of a rotor dovetail groove punching sheet. The tool comprises a press mechanism, a press-fitting bottom plate, a rotor body and a rotor punching sheet, wherein the press-fitting bottom plate is arranged on a press mechanism platform, the rotor body and the rotor punching sheet are arranged on the press-fitting bottom plate, a pull rod hole and a dovetail groove are arranged on the rotor punching sheet, a pull rod hole positioning bar is arranged in the pull rod hole, a dovetail groove positioning bar is arranged in the dovetail groove, and a press-fitting pad is arranged above the rotor punching sheet. The lamination method comprises the following steps of firstly, carrying out lamination on the press-fitting bottom plate, wherein the positions of the pull rod hole and the dovetail groove are kept away during lamination; ensuring a groove shape by the pull rod hole and the dovetail groove of the positioning punching sheet; and finally tightly pressing the punching sheet by using the press-fitting pad. The invention provides the lamination tool and method of the rotor dovetail punching sheet, and a high-quality rotor iron core can be simply and rapidly obtained.