In this study, the hydrophobic spun polyester yarn was carried out by the yarn dyeing machine. Mixing hydrophobic agents with the packaged yarn and heated circulating for 20 minutes, the hydrophobic spun polyester yarn could be obtained after cooling and drying. The color difference of yarn generated by hydrophobic treatment is less than 2, and 20 times washing durability could be reached. The process is simple and no special equipment is required, so mass production of hydrophobic yarns in possible.