The micro-physical structures of cloud and , snowfall in precipitation starting stage were observed with a instrument aircraft on Nov. 7, ,1,983. The results show that there were several cloud layers in the, starting .stage of cold front snowfall, and there was a snow band with 5 km .width over the cold front.It is estimated that the updraft velocity is greater than 0.8 m·s^-1 in the snowband,which is somewhat characterized by a narrow con-vective cells band.The ice crystals were formed at the top of the convec-tive" cloud band with temperature about -17℃.