A method of measuring atmospheric transmittance from a single frame of multi-spectral image for non and weak absorption waveband was proposed, which can be applied to evaluate and correct atmospheric attenuation effect in optoelectronics engineering field. Firstly, a radiometric image can be acquired using the camera with absolute radiometric calibration; secondly, according to the optical model of image degradation in atmosphere and the dark channel prior statistical theory, average atmospheric transmittance of dark channel can be calculated from radiometric image; finally, the atmospheric transmittance of specific wavelength is calculated using the average extinction coefficient relation database of the specific wavelength and the dark channel waveband. The experimental comparison indicates that the correlations between the transmittances measured by the new method, visibility meter and lidar are good. For the new method and visibility meter, the correlation coefficients are between 0.89 and 0.95, and the average relative deviations are no more than 9%, 15%, 30% for 1km, 4 km and 6 km, respectively; while for the new method and lidar, the correlation coefficients are between 0.95 and 0.97, and the average relative deviations are no more than 6%, 9%, 18% for 1 km, 4 km and 6 km, respectively.