To correct the attenuation of radar echo at millimeter-wave band, stratus cloud, precipitating stratus cloud and convective cloud echo data were chosen as sample for the test. Method of bin-by-bin correction in the groups was used according to the empirical relationship between radar reflectivity factor Z and attenuation coefficient k. The results show that, in cases of stratus clouds with weak echo, the corrections are minor and these echoes are almost right. On the contrary, in case of rainfall, both water droplets and rich water vapor along the ray path will cause strong attenuation, and it is difficult to carry out the correction. After attenuation correction, the quality of millimeter wavelength radar data is definitely improved though difference is still existed.