In order to get the precision measurement of birefringence of quartz crystal at the communication wavelength1310nm, based on the principle of precision measurement of phase difference between P and S polarized lights of spectroscopic ellipsometer, a method for precision measurement of birefringence of crystal was designed through the analysis of the Jones matrix under the transmission mode, and the precision measurement of birefringence of quartz crystal at 1 310 nm at room temperature (22 ℃) was made, the measuring results and error analysis show that the precision reached 10-6 level, this is the most precise birefringence parameter available, and it is of important significance for the improvement of designing precision of phase retardation devices of quartz.