The early Paleozoic sedimentary basin, outcropped in the Lajishan mountain of the central Qilian orogeny, is fault contact relation with the Lajishan mélange composing of conglomerate, sandstone and siltstone. The rocks have been previously considered to represent a Silurian sequence because of lack of reliable age evidence. This study shows that the ages of detrital zircons from the sandstons are predominantly early Paleozoic, and the youngest detrital zircon grains clearly constrain that the maxium depositional age of the sedimentary sequence is ca. 413±5Ma. The ages of detrital zircons can be evidently divided into four groups:411～516Ma, 619～1149Ma,1500～1621Ma and 2356～2549Ma. Zircon with ages from 411Ma to 516Ma comprises 56.6% of the detrital zircon population, and were mainly sourced from the Qilian orogenic belt in adjacent regions. These detrital zircons in the 411～516Ma age population show approximately the same proportion of positive and negative εHf（t） values ranging from -11.1～+137, correlating with the series of igneous rocks caused by the northward subductionaccretion and collision of central Qilian in the Caledonian period. Zircon with ages from 619～1149Ma comprises 278% of the detrital zircon population, and shows the εHf（t） values ranging from -189 to+95. The age data are comparable with those zircons in the Neoproterozoic granites and volcanic rocks in the central Qilian block. The subordinate detrital zircons with ages from 1500Ma to 1621Ma and from 2356Ma to 2549Ma show mainly the negative εHf（t） values, which indicate that the material sources were probably derived from the basement of the Qilian orogenic belt and the North China plate. A comprehensive analysis shows that the material sources of late Silurian basin were characterized by obvious diversity, derived from the Qilian orogenic belt and the North China plate，and the Lajishan mélange is most significant source contribution to the sediment.