The Bayanbulak Basin is an intermontane valley of the basin-and-range of the Tian Shan mountains, to the north of the Tarim Basin. The total area of grassland is , of which the reserve itself covers . The Kaidu River runs from west to east through the area, at times meandering and leaving cutoff lakes, and is fed from streams from the high ranges of the Tian Shan to the north and south. The rivers are meandering and braided over gravel beds. In 1982, the Du-Ku highway was built across the Tian Shan, greatly opening access to the area.