Based on the double light-path experiment device measuring for diffraction efficiency of diffractive optical elements(DOEs), a correcting formula of diffraction efficiency was introduced to ensure the measurement accuracy of diffraction efficiency when light of secondary order diffraction was received by the detector after passing through the pinhole aperture. The diffraction efficiency of the designed hybrid refractive-diffractive optical system was measured at three laser wavelengths over the visible waveband for the incident angle upon microstructure surface was 12°. The measurement results were simulated and analyzed. Due to some manufacturing errors and blocking effect, the measured diffraction efficiency was smaller than the theoretical. Based on the fitted curve of measurement results, the deviation of the polychromatic integral diffraction efficiency from the theoretical value was 12.84% over the 473-632.8 nm waveband.