In the western segment of the Haiyuan Fault Zone, the Laolongwan Basin's sedimentation encompasses a suite of late Cenozoic red clastic deposits, which document the developmental processes of the northeastern periphery of the Tibetan Plateau. The lack of refined stratigraphic chronology research has led to a generalized classification of these late Cenozoic deposits under the Neogene Gansu Group, sparking debates about the Laolongwan Basin's geological response to the northeastward expansion of the Tibetan Plateau. This study, grounded in a 1:50000 scale regional geological survey, undertakes an in-depth magnetostratigraphic chronology analysis of the Laolongwan Basin's late Cenozoic strata, resulting in the establishment of a magnetostratigraphic chronological framework spanning approximately 13.61~2.58 Ma for the basin. By integrating lithological features and sedimentary environment assessments, the Laolongwan Basin's Neogene Gansu Group strata are differentiated into two distinct lithostratigraphic units: the Xianshuihe Formation (N1x) and the Linxia Formation (N1-2l). The Xianshuihe Formation, dating back to the middle Miocene (ca.13.61~8.11 Ma), comprises a sequence of brick-red sandy conglomerates, blocky medium sandstones, and silty mudstones. This formation is indicative of late Miocene fan delta and shallow lake depositional environments and is characterized by an angular unconformity with the underlying Early Silurian Angzanggou Formation, which consists of greenish-gray metamorphic sandstone. The Linxia Formation, spanning the late Miocene to late Pliocene (8.11~2.58 Ma), is marked by thick layers of shallow brick-red medium sandstone and interbedded medium to coarse conglomerates, with sporadic occurrences of boulder conglomerate. This formation displays a distinctive "sand-gravel interlayering" arrangement and is associated with fluvial depositional processes, exhibiting a parallel unconformity with the preceding Xianshuihe Formation. On a regional scale, the Neogene Gansu Group's Xianshuihe and Linxia Formations within the Laolongwan Basin can be correlated with contemporaneous strata in adjacent areas. This correlation aids in harmonizing the Neogene stratigraphic framework of the Tibetan Plateau's northeastern margin and provides essential stratigraphic insights for investigating the Cenozoic tectonic uplift of this region.