Belfort M6400 is a lower-cost and more efficient visibility observer produced by Belfort Instruments on the basis of M6000 in terms of software and hardware. This paper uses the Belfort M6000 visibility meter and the Belfort M6400 visibility meter observation data of the Panyu National Meteorological Observatory from June 11 to July 11, 2021 for comparison experiments, and analyzes the characteristics of the observation differences and meteorological elements of the two visibility meters. relation. The results show that (1) The change trend of the average minute visibility observed by the two visibility meters is relatively consistent, and the correlation coefficient between the two is 0.92; (2) With the increase of the visibility level, the range of difference and the degree of dispersion both increase; ( 3) The observation values of the two visibility meters are negatively correlated with relative humidity, positively correlated with air pressure, and have no obvious relationship with other meteorological elements; (4) The daily average correlation coefficient (0.93) of the two visibility meters in rainy days is more than It is higher on sunny days (0.82).