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Visibility is an important element in meteorological, environmental and transport departments. The unified test environment and calibration standards have not been made for different visibility meters, which leads to great disparity in the results. For the unified environment, a simulation cabin has been developed. Visibility from 10 m to 50 km is simulated by fog generators and purifiers. A method has been put forward, which can eliminate the errors caused by the unevenness of air. Different models and the forward scattering visibility meters of the same model have been tested. The result shows that the difference in different models is greater than 100%. The relative error is within the range of ±5% in the same type. A correction method has been developed, which will decrease the relative error within the range of ±10% in different types.