Flat polyester fiber

The utility model relates to a flat polyester fiber and belongs to the technical field of chemical fibers. The flat polyester fiber comprises a fiber body (1), wherein the cross section of the fiber body (1) is in a three-section structure, a middle section is in an oval flat shape, a left section and a right section are round, the middle section and the left section as well as the right section are in circular arc transition, an oval cavity (2) is formed in the center of the middle section, round cavities (3) are formed in centers of the left section and the right section, a plurality of spherical bulges (4) are uniformly arranged on the outer surface of the fiber body (1), and an antibacterial agent layer (5) is arranged on the surface of the fiber body (1). According to the flat polyester fiber, the curling elasticity is good, the strength is high, and the hygroscopicity, the breathability and the heat insulation property of a fabric can be improved.