The structure and measuring principles of laser raindrop spectrometers are described, and comparison is conduced between rainfall measurements observed synchronously by a laser raindrop spectrometer and automatic meteorological station. The relationship between rainfall and radar reflectivity obtained by a new generation Doppler Rader is discussed. It is found that the temporal variation tendencies of the rainfall intensities observed by the laser raindrop spectrometer and automatic meteorological station are similar, but the variances of the intensities are different. The maximum rainfall intensity observed by the laser raindrop spectrometer is much larger than that obtained by the automatic meteorological station, and the appearing time observed by the laser raindrop spectrometer is much earlier. Through contrastive analyse between the two kinds of rainfall measurements with radar reflectivity, it is concluded that the rainfall probed by the laser raindrop spectrometer in good accord with radar reflectivity.