According to the verification regulations for rainfall sensors of automatic meteorological stations and the procedures and methods of measurement uncertainty evaluation, the sources of measurement errors and the resulted measurement uncertainty are analyzed. Using different types of evaluation approaches and different mathematical calculation methods, the standard uncertainty for each component is evaluated, and ultimately the expanded uncertainty of the indoor verification measurement results of the SL3 1 double tipping bucket raingauge is given. For two types of precipitation intensity, the measurement uncertainty 〖WTBX〗U〖WTBZ〗95=014 mm, and the coverage factor 〖WTBX〗k〖WTBZ〗95=206 The verification by the comparative transmission method indicates that the measurement uncertainty meets the requirements of the related rules for the examinations of both measurement standards and legal metrological verification service. This evaluation method can improve the work flow and the quality of indoor rainfall sensor verification.