In this paper, the polyester fiber surfaces were modified with the combined method of causticization and low-temperature plasma. The effect of Alkali pre-treatment on plasma treatment was studied to investigate the influence of the combined treatment on the properties of the polyester fibers. Through changing the process parameters, such as the temperature of causticization and the plasma treatment duration, the changes of weight loss, mechanical properties, wetting properties and dyeing properties of the polyester fibers after the causticization-plasma treatment were analyzed. In addition, the change of the surface morphology and chemical composition of the polyester fibers after the treatment was investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) analysis respectively. The results showed that the wetting and dyeing properties of the polyester fibers were improved in a higher degree after causticization-plasma treatment than the causticization and plasma treatment independently. Meanwhile, the wetting and dyeing properties were improved more significantly with the increase of the causticization temperature in the causticization-plasma treatment. It was concluded that the pretreatment of the causticization before the low temperature plasma treatment can accelerate the etching and oxidization towards the polyester surface during the plasma treatment.