In order to measure velocities of explosion loading surface driven by blast waves, a compound velocity interferometer was introduced. The illumination laser from fiber array was projected onto the target surface through a telecentric optical imaging system. Only several points on the target were illuminated, which got the utmost out of laser power. The illumination beam had so small numerical aperture that the illumination spot size kept constant while the target moving within 10 mm. A taper fiber array with large core diameter was mounted on the image surface of optical imaging system, thus the signals could coupled into the large core fibers effectively and could output in single mode for difference interference in single mode Mach-Zender interferometer during the target movement. A 45° beam splitter with a small wedge angle was employed before the first optical element of the imaging system, the illumination laser could be reflected to the object surface by the rectangular films on the first surface of the splitter. The small wedge angle of the splitter could compensate the astigmatism lead by titled parallel plate. During the object surface moving within 10 mm, the lighting power and spot sizes on object surface remain the same, and the coupling efficiency of Doppler frequency shift signals also remain constant. This optical system could meet the demand of explosion loading surface velocity measurement in long distance range. © 2017, Science Press. All right reserved.