In order to limit accurate formation time of Hongtubu basic volcanic rocks in the east segment of North Qilian orogenic belt, LA-ICP-MS U-Pb isotope dating technique,
combined with cathodoluminescence image (CL) study,
 was separately used to determine the zircons from pillow basalt and diabase dyke. Two main populations of zircons from Hongtubu pillow basalt were obtained, giving an average ²⁰⁶Pb/²³⁸U ages of（443.4±1.7）Ma and an upper-intercept ²⁰⁶Pb/²³⁸U -²⁰⁷Pb/²³⁵U age of（1 782±34）Ma. Meanwhile, LA-ICP-MS U-Pb analyses for zircon grains from the diabase dyke within Hongtubu basalts yielded a mean age of （385.7±7.9）Ma, and a group of apparent ²⁰⁷Pb /²⁰⁶Pb ages from（1 697±6）Ma to（2 692±4）Ma. With the relevant data synthesized,  Hongtubu basic volcanic rocks were considered to form in the Late Ordovician, corresponding to the age of Chenjiahe medium-acid volcanic rocks which locate in the north of Hongtubu basic volcanic rocks. It was deduced that primitive magma of the basic volcanic rocks was contaminated in different degree by Longshan rock group.These new data have important significance for further research on the tectonic formwork in the east segment of the north Qilian orogenic belt, its tectonic evolution, and the connected relation of North Qilian and North Qinling orogenic belt.