Abstract: The PLA fibers were subjected to various heat treatments.The impact of temperature and duration of heat treatment on the breaking strength,elongation at break,initial modulus and work to break of the fibers was investigated.The results indicate that as the temperature increases,the breaking strength of the fibers gradually decreases and the elongation at break increases.As the temperature and duration increase,the initial modulus decreases.When the temperature is above 130℃or duration over 20 minutes,the treatment will result in significant degradation of the mechanical properties the PLA fibers.