In order to investigate the low liquor dyeing method of poly(ethylene terephthalate) (PET) fiber, a study on two phase dyeing method was studied. The results are as follows: 1. Initial dyeing rate of two phase dyeing method was greater than that of dyeing in water, and the solubility of dye in solvents had much influence on initial dyeing rate, but bath ratio had little. 2. Dye affinity of two phase dyeing method was greater than that of dyeing in water but smaller than solvent dyeing. 3. Diffusion coefficient was greater than that of dyeing in water but smaller than solvent dyeing. 4. saturation value of dye of two phase dyeing method was excellently great than that of water dyeing and solvent dyeing. 5. The decrease of liquor ratio had little influence on the unlevel dyeing in two phase dyeing method. 6. The light and wet fastness of PET dyed by two phase dyeing were nearly the same as that by water dyeing.