Abstract: A comparison was made on the differences of the geographical populations of brown planthopper (BPH), Nilaparvata lugens (St-l), collected from Nanning of South China and from Ha Noi, Ha Tinh, Hue, TP. Ho Chi Minh, and Song Cuu Long of Vietnam. The BPH populations from Nanning, Ha Noi, Ha Tinh and Hue could damage the rice varieties with Bph1 and bph2 genes, whereas the BPH populations from TP. Ho Chi Minh and Song Cuu Long showed stronger virulence to the rice varieties with Bph1, bph2, Bph3 and bph4 genes than the other populations. The survival rates of the nymphs from Nanning, Ha Noi, Ha Tinh and Hue populations on the rice varieties TN1, Mudgo and ASD7 were all above 52%, but those on the rice varieties Rathu Heenati, Babawee and Ptb33 were below 44%. The nymphs of the BPH populations from TP. Ho Chi Minh and Song Cuu Long on the TN1, Mudgo, ASD7, Babawee and Ptb33 had a survival rate of above 50%, but those on Rathu Heenati had a survival rate of below 50%. The nymphal development durations of the BPH populations from Nanning, Ha Noi and Hue were significantly shorter on TN1, Mudgo and ASD7 than on Rathu Heenati, Babawee and Ptb33, but for the BPH population from Ha Tinh, the nymphal development duration on TN1, Mudgo and ASD7, and on Rathu Heenati and Ptb33 had no significant difference. The nymphal development durations of the BPH population from TP. Ho Chi Minh on TN1 and ASD7 were significantly shorter than those on Rathu Heenati, Babawee and Ptb33, but for the BPH population from Song Cuu Long, the nymphal development durations on TN1, Mudgo, ASD7, Rathu Heenati, Babawee and Ptb33 had no significant difference.  After infested for 192 h, the nymph density of the BPH populations from Nanning and Ha Noi was significantly lower on Rathu Heenati, Babawee and Ptb33 than on TN1, Mudgo and ASD7, that of the BPH populations from Ha Tinh was significantly lower on Babawee than on TN1, Mudgo, the BPH populations from Hue and TP. Ho Chi Minh had a significantly lower nymph density on Babawee than on TN1, Mudgo, ASD7 and Rathu Heenati, and the BPH population from Song Cuu Long had a significantly lower nymph density on Babawee and Ptb33 than on TN1 and ASD7. The virulence of the BPH population from Nanning was similar with that of the BPH populations from central and northern Vietnam, which was a new proof that the BPH in South China was migrated from the central and northern parts of Vietnam.