The invention relates to the field of sewage treatment, particularly a sewage treatment method and device. The method comprises the following steps: A: carrying out anaerobic biological treatment on the sewage to obtain a sewage mixed solution; B. by utilizing a driving solution, osmosing water in the sewage mixed solution into the driving solution under the forward osmosis action to obtain an absorbing solution; and C. separating water out of the absorbing solution by electrodialysis. The device comprises an anaerobe reactor, a forward osmosis membrane assembly communicated with the anaerobe reactor, an absorbing solution storage container communicated with the forward osmosis membrane assembly, and an electrodialysis assembly communicated with the absorbing solution storage container.