The Chazang Co-Xainza fault belt is the northern segment of the Xaitongmoin-Xainza fault belt that traverses Gangdise. The northwest-striking Gyaring Co fault is a transform boundary of the Chazang Co-Xainza basin. There are no pre-Neogene sediments in the basin, which cuts Pliocene strata and a twomica granite of 5.45 Ma. Intrusions, strata and structural lines can be correlated on the two sides of the basin from Chazang to Xainza. Sediments of 130 ka are the oldest in the basin. The basin started 30000 a ago and reached a width of 6750-15250 m. So, the extensional speed is more than 5.19 cm/a, which is consistent with the result of GPS. Longitudinal compression and latitudinal extension are two modes of crustal dynamic system in the Gangdise area.