This paper introduced the pore structure and characteristics of the homey microporous modified PET fiber. Two sets of dyeing experiments were carried out to dye four kinds of the modified PET fiber with cationic dyes: one set was experimentalized at different temperature, the other was at different concentration of dyes. The results indicated the optimum temperature was 100 ℃ and dyes concentration 1% ～ 5%（o.w.f）.