Rainfall can bring serious attenuation to the laser signals, so it will take some influence to the laser detection system applied in the rain. The attenuation of laser beam propagating in the rain is lucubrated in the infrared range, but the attenuation of green laser in the rain has not been reported. Therefore, based on Fraunhofer diffraction and geometric optics theory, the attenuation model of laser radiation at 532 nm and 1064 nm by raindrops is founded, and the attenuation characteristics are contrasted and analyzed. Then, the veracity of attenuation model is validated by experiments. Theory analysis and experimental results indicate that the differences of the scattering loss between the two wavelengths are slight, but the absorption of the raindrops to the 1064 nm is obvious, so the transmittance of laser radiation at 1064 nm is lower than 532 nm. Attenuation and transmission characteristics of laser in rain provide theoretical basis for green laser applied in the detection system working in the rain.