This paper reports detrital zircon U-Pb ages carried out by LA-ICP-MS from the Middle Triassic sandstones of the Nanpanjiang Basin, aiming to constrain the provenance of the Nanpanjiang Basin, and to discuss its geological implications. It is suggested that: 1) the main source area of the Nanpanjiang Basin was a magmatic arc formed during Permian on the northern border of Tethys, the southwest margin of South China; and 2) the Nanpanjiang basin is a foreland-basin associated with the closure of the Paleo-Tethys ocean along the Song Ma zone（in Vietnam）, and the Song Ma zone is a suture, rather than an intraplate reactivated zone between South China and Indochina Block.