Laser Doppler velocimetry technology has the advantages of non-contact,wear-free and high precision. It is widely used in high-precision velocity, acceleration and length measurement in industry, navigation, aerospace and other fields. Dual beam laser Doppler velocimetry has the characteristics of simple structure and strong anti-interference. In order to improve the measurement accuracy of dual beam laser Doppler velocimetry, this paper introduces a double beam laser Doppler system for measuring the linear velocity of circular rotation. When the linear velocity of the target is 1 596.6 mm/s, the theoretical value of laser Doppler difference frequency signal is 0.975 MHz. The measurement angle is 0°, and the difference frequency signal observed in the experiment is 1.013 MHz, with an error of about 3.8%. Furthermore, by changing the different angular positions of the observer, the measured Doppler frequency shift and 0° frequency shift error are within 0.8%. Results show that the measurement system can measure the Doppler frequency shift signal of moving objects and change the observer angle of dual beam laser Doppler velocimetry without affecting the measurement results. This experiment provides a useful reference for the development of this kind of sensor.