An outer finned tube includes a tube body, an outer wall of the tube body is provided with outer fins spirally arranged in an extension direction of the tube body; grid fins are arranged between two adjacent spiral parts of the outer fins correspondingly; two ends of each grid fin are connected to the two adjacent spiral parts of the corresponding outer fin respectively; a gap is kept between each grid fin and the outer wall of the tube body; and the plurality of grid fins are spaced in the extension direction of the tube body. An enhancing cavity is formed in an area defined by the outer wall of the tube body, inner walls of the grid fins and the outer fins in an encircling way, which can form a larger degree of superheat, provides a nucleation point for a boiling/condensation process and improves a heat exchange performance.