We report the discovery of an accretionary lapilli-bearing tuff layer from Keping, NW Tarim Basin. There occurs a widely-spread felsic pyroclastic sequence between the Kupukuziman basalts and the Kaipaizileike basalts. The felsic pyroclastic sequence, underlain by synchronous basaltic tuff and basalt lava flows, consists of an air-fall tuff layer with occasional cross beddings, three accretionary lapilli-bearing tuff layers, an ignimbrite layer and a re-sedimented ignimbrite layer. The zircon U-Pb age of an ignimbrite from the felsic sequence is 290.9 ± 1.3 Ma (MS WD = 1.12), which determines the cessation time of the Kupukuziman basalt eruption. Based on their structural characteristics, the accretionary lapilli can be classified into three types. They have typical characteristics of ash aggregates formed in co-ignimbrite ash fall deposits, e. g., maximum grain size of accreted ash <250μm, and aspect ratio > 1.5. The stratigraphic evolution of Type II-I-III indicates an undulating strength of a pyroclastic flow that supported the formation of accretionary lapilli.