Abstract: A swirl-type demulsification and dehydration device for oil-water emulsions, including a swirler. An open end of a swirl chamber of the swirler faces towards an underflow pipe and communicates with the underflow pipe through a composite curved pipe section coaxial with the swirl chamber. A large-diameter end of a concave arc transition section is connected to the open end of the swirl chamber, is the same with the swirl chamber in inner diameter. A large-diameter end of a straight cone transition section is tangent to a small-diameter end of the concave arc transition section. A small-diameter end of the straight cone transition section is tangent to a large-diameter end of a convex elliptical arc transition section. A small-diameter end of the convex elliptical arc transition section is connected to the underflow pipe.