Abstract: Based on the contact relationships, sedimentary cycles, sedimentary systems and lithofacies and lithologic characteristics of the stratigraphic section, the Pliocene fluvio-lacustrine sediments in Zanda basin are divided into 2 formations, 5 sedimentary facies and 8 lithologic members. The first lithologic member of the Guge Formation consists of conglomerate, belonging to fluvial deposits; the second, third and fifth members are dominated by fine clastic rocks, belonging to shallow lacustrine deposits; and the fourth member consists predominantly of clayey fine clastic rocks, belonging to deep lacustrine sediments. The first, second and third members of the Toling Formation consist of a sequence of clastic rocks including conglomerate, pebbly and coarse- and medium-grained, calcareous feldspathic litharenite and medium and fine sandstone, belonging to typical alluvial (diluvial) fan deposits. ESR and paleomagnetic dating indicate that the age of the fluvio-lacustrine sediments of the Guge Formation is late Pliocene (4.40-2.47 Ma) and the age of the Toling Formation is early Pliocene (5.44-4.40 Ma) in the Zanda basin. The Zanda basin is a syngenetic downfaulted basin. Its evolution progressed through three stages: the transgressive systems tract, lake expansion systems tract and lake shrinkage systems tract during the Pliocene tectonic movement.