In order to meet the high reliability requirement of velocity measurement in shock wave and detonation experiments, a new velocity measurement method named dual-wavelength laser interferometer was proposed based on wavelength division multiplexing/demultiplexing technique. A verification system was designed with 1550.0 and 1530.3 nm wavelengths, and the dynamic verification experiments under low- and high- speed conditions were carried out on the light gas gun. The dynamic experimental results show that the free surface velocity of the sample can be measured independently with a single optical fiber probe, and the velocity measurement results obtained at two wavelengths exhibit good consistency, with the relative deviation of the velocity within ±1.5%.