Making use of rainfall attenuation in microwave links is a brand new way to detect rainfall intensity, which can collect abundant meteorological observation information relying on the worldwide microwave communication networks. On the basis of analyzing rainfall attenuation, the 15〖CD*2〗20 GHz microwave link rainfall measurement experiment was conducted, in which the microwave communication link distance of 6 km and the mean values of receiving level before the rainfall are chosen as reference values. The rain attenuation is calculated by means of the reference value and the actual receiving level. The result shows that the 15〖CD*2〗20 GHz microwave can be used to measure the instantaneous rainfall rate at a more detailed temporal resolution; the rainfall attenuation can be exactly detected when the rainfall intensity is between 2 and 70 mm/h. The retrieved rain attenuation values are correlated with the actual measurements. The errors and their reasons in this experiment are also analyzed, which provide references for the further research, such as forward modeling.