The invasion of Bemisia tabaci (Gennadius) Q biotype into Xinjiang was confirmed based on mtDNA COI sequence examination for 11 populations in Xinjiang, NW China. More than 30 whiteflies collected, (min.10 individuals tested from each population) in 2008~2010 from Urumqi (86°40′~88 °55′E, 43°15′~44°20′N), the capital city of Xinjiang, Northwestern China and from the city of Turpan (88°05′~89°54′E, 41°20′~43°35′N), an outbreak region of B.tabaci 195 km E of Urumqi. The following samples collected in 2010 proved to belong to the Q biotype: the population HH1 collected at a flower market on poinsettia in Urumqi， populations of LJ on hot pepper， XHS on tomatoes， QZ on eggplant， YC on tobacco, all collected from in greenhouses near Turpan. The population HH2, collected at a flower market on poinsettia in Urumqi in 2010 and samples collected before 2009 (including population JK-S collected outside on wild mallow in Urumqi, population ZHO collected on cotton in greenhouses in Urumqi， and populations of TC1， TC2， TC3 collected from cotton fields in Turpan), were still confirmed as belonging to the B biotype.