Abstract: The feasibility of dyeing polylatic acid fiber with supercritical CO₂fluid is studied for solving the problems of larger amount of water consumption and effluent discharge from dyeing of fabrics.This paper studied the effect of temperature,time and pressure on dyeing and mechanical properties of fibers.The optimal technological conditions were determined by orthogonal experiments.The results showed that deeper shade could be achieved in supercritical CO₂medium than in water at the same temperature;TheK/Svalue of PLA fiber was better with the increasing of temperature;K/Shad a biggest value when the pressure increased or time prolonged;color yield not always depends on the increasing of pressure or time.The best processing conditions were : dyeing temperature 100℃,time 40 min,pressure 20 MPa.