According to the measuring principle of diffraction efficiency for diffractive optical elements, the double light-path measurement device of diffraction efficiency is set up. The advantages of double light-path measurement are briefly introduced. For the measurement device of diffraction efficiency for diffractive optical elements, the factors having influence on the accuracy of the measurement results are discussed by the reasonable choices of the pinhole aperture of the measurement device, the light of the main diffraction order can be received by the detector, and the secondary diffraction light will be filtered out, ensuring the accuracy of the measurement results. The diffraction efficiency of the designed hybrid refractive-diffractive optical system is measured at three laser wavelengths over the visible waveband. The measurement results are simulated and analyzed. The deviation of the measurement results from the theoretical value is less than 5.0% over the 473~632.8 nm waveband. The double light-path measurement device can be used to measure the diffraction efficiency of diffractive optical elements.