The major types of virus diseases of soybean occurred in the North-East China are yellow mottling,top necrosis,rugosity and leaf curl etc.From the results of identification of 50 isolates,it was demonstrated that the diseases were mainly caused by different strains of soybean mosaic virus,namely SMV-Y,SMV-T and SMV-C They were transmitted by sap easily,and by Aphis glycines and seeds also.They may infect soybean and Glycine gracilis systemically,and induce local lesions on bean variety Jia-qiao-dan,but may not infect other speices of Leguminosae or other families.The DEP was 10^-2,TIP was 50-55℃. and LIV was 12 hours to 2 days.The virus particles were flexous rods about 1000nm.long.There were cross-protection reactions between SMV-Y and SMV-T.