In order to improve the resolution of the laser Doppler vibrometer (LDV) and measure surface microvibration, an LDV equipped with a dual-frequency ring laser is proposed. The source and optical path structure of the system are introduced, and the measurement principle is derived. The dual-frequency ring laser, modified by a multioscillator ring laser gyroscope with stable frequency difference and narrow linewidth, can emit two beams in two directions and the two beams show a certain angle and have a fixed frequency difference. Combined with the grating technology, the surface transverse microvibration measurement can be realized. Compared with other LDV, the system has simple optical path and high resolution, and the maximum noise of amplitude resolution is lower than 0.012 μm·Hz^{1/ 2} in the laboratory experiment.