The invention provides a production device for a high-molecular-weight polyether macromonomer for a polycarboxylate superplasticizer. The device comprises a first-grade pre-reaction unit, a second-grade main-reaction unit, an after-treatment unit and an ethylene oxide feeding pipe, wherein the first-grade pre-reaction unit comprises an external circulation reactor, a circulating pump, a heat exchanger and an intermediate storage tank which are in successive connection, wherein the lower part of the external circulation reactor is provided with an initiator inlet, and the top part of the external circulation reactor is provided with a circular first atomizer connected with the heat exchanger; the second-grade main-reaction unit comprises a main-reaction kettle, wherein the interior of the main-reaction kettle is provided with a dual-impeller type agitator, and the bottom part of the main-reaction kettle is provided with a feeding distributor; and the after-treatment unit comprises an after-treatment kettle, wherein the interior of the after-treatment kettle is provided with a single-impeller type agitator, and the top part of the after-treatment kettle is provided with a second atomizer and a vacuum recovery pipe. The apparatus provided by the invention adopts a double-stage type reaction system and uses an intermediate tank for temporary transition, so process flow operation is simple; double-stage reactions are free of mutual interference; semi-continuous production can be realized; and production efficiency is greatly improved.