The invention relates to an oil-water separation method and a device, which comprises the following details: a helix tube is arranged; the helix tube is divided into a top tube and a bottom tube which are integrally communicated; the tube wall of the inner side of the bottom tube is provided with a plurality of holes at intervals; the center of the bottom tube is provided with an oil collecting pipe; the pipe wall of the oil collecting pipe are connected with the corresponding holes by a plurality of connecting pipes; the density difference between oil and water and centrifugal force generated by an oil-water mixture which rotates and flows in the helix tube are used for causing aqueous phase liquids with greater density to move towards the outer side of the tube wall of the helix tube and oil phase liquids to gather towards the inner side of the tube wall of the helix tube under the pressure effect of the aqueous phase liquids; the separated aqueous phase liquids and the oil phase liquids outflow respectively by an aqueous phase liquid outlet at the bottom of the helix tube and an oil phase liquid outlet at the bottom of the oil collecting pipe. The thread pitch of the helix tube is larger than or equal to one times of the external diameter of a tube of the helix tube or less than two times of the external diameter of the tube of the helix tube; therefore, the volume of a separation system is effectively reduced and the separative efficiency of the oil-water mixture is effectively increased, thus causing the oil-water separation to be more accurate. The invention can be widely applied in various oil-gas field separation systems.