A directional coupler and a receiving or transmitting device. The directional coupler includes: a primary signal line composed of a metal rod; and a coupled signal line composed of a microstrip line in a curved shape on a printed circuit board; wherein the medium between the metal rod and the microstrip line is air. Compared with existing directional coupler, the directional coupler of the embodiments of the disclosure has a lower transmitting loss, a large power capacity, and a high directional qualification. The directional coupler is capable of ensuring a higher passive intermodulation qualification. The advantages of the embodiments of the present disclosure are easier assembly, good uniformity of the qualifications, and adaptability for various application environments. The directional coupler of the disclosure ensures different parameter qualifications, and is simple to assemble, so that the low cost is achieved.