The invention discloses a technology for dyeing polyester fibers. The technology comprises the following steps: (1) pre-treating: immersing the polyester fibers in a pre-treatment solution, heating the solution to 80-85 DEG C, keeping the temperature for 30-50 min, cooling the solution to normal temperature, and drying the pretreated polyester fibers; (2) carrying out enzyme treatment: immersing awool fabric in an enzyme treatment solution at a bath ratio of 1:(20-25) for 60-80 min, wherein the enzyme treatment solution contains 35-45 mL/L of hydrogen peroxide and 35-45 [mu]/mL of acid protease, and the pH value of the enzyme treatment solution is 9.6-10.4; (3) dyeing: placing the loose polyester fibers in water at a bath ratio of 1:(10-15), sequentially adding acetic acid, a low-temperature dyeing assistant and a disperse dye, and performing uniform stirring for 20 min; (4) fixing the color: carrying out hot steaming on the polyester fibers obtained in step (3) by color fixing solution steam for 1-1.5 h, and cooling the steamed polyester fibers to room temperature; and (5) post-treating: taking out the obtained polyester fabric, washing the polyester fabric with water 2-3 times,carrying out reduction cleaning, washing the cleaned polyester fabric with water 3-4 times, and drying the polyester fabric at 80-85 DEG C. The polyester fiber obtained in the invention is uniformly dyed, and does not shade after being washed.