Dark channel prior has a good effect on haze removing. A visibility measurement method based on dark channel prior is proposed, which can overcome the disadvantages of high cost and difficulty in building up of the meteorological visibility meter. The proper target region is selected by analyzing different regions of the image so as to estimate transmittance. A more accurate transmittance is obtained by haze removal parameter optimization and guided filtering refinement, and then the atmospheric extinction coefficient and visibility are inferred. Comparing the results of dark channel prior with the data measured by forward scattering meter (CJY-1G), the error is within ±15%, which meets the application requirement of World Meteorological Orgnization.