In order to measure the residual birefringence and direction angle of fast axis simultaneously, with the advantage of high speed, high precision, high sensitivity, easy operation, good stability and low cost, the photo-elastic modulator (PEM) and electro-optic modulator(EOM) are combined, and the detector is used to detect signals and the locked-in amplifier is used to achieve the first harmonic term. Value and direction of birefringence are solved out by the direct current (DC) term and the first term in the computer, so the simultaneous measurement of value and direction of birefringence in a single photo-elastic modulation channel are realized. The principle of the new scheme is analyzed, and the experimental system is set up. The system is calibrated by the method of instrument offset, and the experimental analysis of a Berek polarization compensator is carried out. Experimental results show that the system calibration can effectively eliminate the measurement error maybe introduced by PEM and EOM themselves. The measuring accuracy and repeatability rate of residual birefringence for this scheme are better than 99.16% and 0.0082 rad, respectively. The measuring repeatability of direction angle of fast axis is 0.06°. This scheme has the advantages of stable operation, high repeatability rate, fast measurement speed, low cost, and conducive to industrial automation integration and so on.