A laser Doppler rotary velocity measurement method based on an all-fiber homodyne interferometer is proposed in this paper. In this method, the target rotary velocity is measured by the difference of two Doppler frequencies, detected by two homodyne interferometers with a single photodetector (PD), which can be located anywhere on the side of the turntable, and then the rotary velocity can be measured very flexibly without measuring the incident angle. This method can miniaturize the dual-beam rotary speed measurement device. The experimental results show that the relative errors are below 0.5%.