Detrital zircons LAICPMS UPb dating was performed systematically on the Late Devonian Dacaotan Group in the conjunction area of North Qinling and Qilian. Three formations of Dacaotan Group are characterized from lower to upper by the followings. ①With decreasing stratigraphic age, the proportion of pre550 Ma grains in the three units decreases from 36% to 32%，and then to 25%. The minimum age of the youngest detritalzircon population decreases upward from 403 5Ma in the bottom, through 385 5Ma in the middle, to 375 6Ma in the top of the group. These trends are consistent with the hypothesis that the Dacaotan Group represents a synmagmatic sedimentary basin, deposited in front of the active continentalmargin magmatic arc. ②The systematic increase in the proportion of the 750~2600Ma zicons from 54% to 65%，and then to 72% upward with stratigraphy height, is accompanied by an increase in the peak age of Proterozoic zircons on the age histograms. These trends may reflect increased uplift and erosion of the orogen basement, and/or inward denudation of the continent crust with the transverse drainage system. The detrital zircon geochronological results from the Dacaotan Group provide detailed insights into both the provenance of sedimentary formations, and their tectonic history. Our data confirm that the basement of North QinlingQilian microcontinent was the predominant source area for the sediments, the active magmatic arc and recycled collision orogen should be another important source area, and some detritus was derived further from the western block of the North China Craton. In the middle Devonian, an early arc(microcontinent)continent collisional orogen was overprinted by the Andeantype magmatic arc along the southern convergent margin of North China continent. Large volume of molasse sediments has been shed into forearc basins at this time, presumably resulted from the combined effects of the collision and the southern oceanic crust subduction northwardly. Siliciclastic rocks of the Upper Devonian Dacaotan Group record rapid tectonism denudation and sedimentary response during this period.