Disclosed is an oil and water supergravity polymerization and separation device. The invention mainly aims at providing a novel separating device used for oil and water two-phase medium separation. The device is characterized in that a first-stage variable pitch pressurization flow path and a reducing polymerization inner core are arranged in a polymerization outer cylinder, a main body of the reducing polymerization inner core is a cone body, a second overflow pipe segment penetrates the reducing polymerization inner core, a second-stage variable pitch pressurization flow path is arranged in a reducing separation cylinder, and a cavity, located below the second-stage variable pitch pressurization flow path, in the reducing separation cylinder is a medium main separation cavity. According to the device, the hydraulic polymerization technology and the rotational flow separation technology are combined, discrete phase oil drops are polymerized under the supergravity effect, before the oil phase is subject to rotational flow separation, small oil drops become large oil drops, it is ensured that the oil phase is in the position close to an overflow opening in the radial direction, the oil and water separation efficiency and precision are improved accordingly, and shortcomings of rotational flow separation and polymerization separation are overcome.