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The measurements of visibility sensors from 22 stations of the Guangdong Automatic Observing System of Visibility are analyzed by compared with the manual observation data of visibility. The results show that the visibility from two approaches had a similar distribution in Guangdong: visibility in coastal areas is higher than that in inland areas; visibility in the east is higher than that in the west; and the Pearl River Delta and the eastern inland have the lowest visibility in Guangdong. The reasons affecting the accuracy of automatic visibility observation include the limitation of visibility sensors, the types of aerosols, and meteorological conditions. After correcting, RMS is smaller than 3 km when the visibility is low, and smaller than 8 km (the mean value is about 6 km) when the visibility is high. Using the statistic method to correct the measurements of the visibility sensor helps reduce metrical errors effectively. After correcting, the Visibility Automatic Observing System in Guangdong can satisfy the needs of automatic observation, especially for low visibility events.