With the characteristic of small twist birefringence in single mode fiber(SMF) an all fiber polarization measurement system is designed.The operating principle of the system is given,and the measurement accuracy is analyzed by method of Jones matrix.The experimental results demonstrate that all fiber polarization measurement system which is consisted of two fiber polarizers with the extinction ratio(ER) of 50 dB and servo motor with angle resolution of 5 000 step/rotation has polarization measurement range of more than 40 dB and measurement resolution of 0.05 dB.The repeatability and stability of the system have been improved compared with that which is consisted of discrete optic devices.The system is easy to operate with simple structure.