Abstract: A new high-precision low frequency phase calibration standard has been developed by using a technique of phase error demultiplication. The frequency range is from 20 Hz to 100 kHz (discrete frequency). The phase shift is from 0 to (n×360) degrees, where n is an integer. Theresolution is (3×10^-8×F) degrees, where F is in hertz. The accuracy is ±(1×10×F±0.001) degrees. The distortion is better than 1×10^-5/10min.