The essential factor for determining the operational capability of automatic weather stations is its reliability; the purpose of operational capability assessment of automatic weather stations is to guide the establishment and improvement of the support and maintenance system for automatic weather stations. Based on a measurement model of atmospheric transparency, the reliability of automatic weather stations is discussed and the physical meaning of the exponential distribution of product reliability is explained. According to the model, the operation capacity (MTBF: Mean Time Between Failures) of the automatic weather stations is defermined by its relibility after adjusting the collection of data, and calculating the relevant evaluation parameters. The MTBF and the minimum time to fail (with the confidence level being 095) of the experimental products were obtained by experiments. The MTBF and the average maintenance cycle of the double or three station system that will be implemenfed are discussed, which can provide technical support for scientific decision making.