The invention relates to an oil-water separation device and an oil-water separation method. The oil-water separation device comprises a cyclone pipe component, a ladder-shaped pipe component and a vertical pipe component, which are sequentially connected, wherein the cyclone pipe component comprises a cyclone pipe body, a liquid inlet pipe, a first oil outlet pipe and a first water outlet pipe, the liquid inlet pipe is perpendicularly and tangently connected with the cyclone pipe body, the first oil outlet pipe is connected to the top of the cyclone pipe body, and the first water outlet pipe is perpendicularly and tangently connected with the lower end of the cyclone pipe body; the vertical pipe component comprises a vertical pipe body, a second oil outlet pipe and a second water outlet pipe, the second oil outlet pipe and the second water outlet pipe are respectively connected to the top and the bottom of the vertical pipe body, and a first inlet and a second inlet are respectively formed in the upper end and the lower end of the vertical pipe body; the ladder-shaped pipe component comprises a first horizontal pipe, a second horizontal pipe and a vertical pipe, and the first horizontal pipe and the second horizontal pipe are relatively parallel; the first end of the first horizontal pipe is connected with the first oil outlet pipe, and the second end of the first horizontal pipe is connected with the first inlet; the first end of the second horizontal pipe is connected with the first water outlet pipe, and the second end of the second horizontal pipe is connected with the second inlet. The oil-water separation device is easy to operate and efficient in separation.