Abstract: A series of brecciaous limestone sedimentary assemblages are developed in the Duoquanshan formation of Dameigou area, Qaidam basin. The assemblages show characteristics of storm deposits macroscopically and microscopically and belong to tempestite resulted from storm action. The storm sedimentary structures in the area mainly include basal erosion structure, coarse-grain lag deposit, hummocky bedding, parallel bedding and horizontal bedding. Observed under microscope, bioclasts and sand cuttings commonly mix with each other in the tempestite which is characterized by secondary pores and stylolite. Based on the different sedimentary sequence assemblages, the storm deposits in the study area are classified into in-situ storm deposit, near-source storm deposit and distal storm deposit, and corresponding sedimentary environment patterns are established. The discovery of the storm deposits indicates that the study area lied in a low-latitude neritic margin-slope environment during the Early Ordovician, which provides geological evidence for the studies on paleo-latitude and plate evolution and has great significance in paleogeography restoration and petroleum exploration and development.