As one of the ubiquitous accessory mineral in granitoids, apatite can effectively monitor the variation of the parental magmatic melt and volatiles and serves as an important tool for tracing the petrogenesis of granitic intrusions and the related magmatic process. This paper conducts micro-area structure and in-situ major and trace element geochemical analysis of the apatite from the Haisigou monzogranite and granodiorite in the East Kunlun Mountains, and combines partial whole-rock geochemical studies to meticulously analyze the genetic types, magmatic physical and chemical conditions, and their evolutionary processes of granites. Furthermore, it explores the formation and evolution mechanisms of granitic intrusions. The results show that apatites in the monzogranite exhibit obvious oscillatory zonation, while apatites in the granodiorite lack any types of zonation. And all the apatites in the monzogranite and granodiorite show similar characteristics to rich-F apatites in composition. The apatite major and trace element compositions and whole-rock geochemical data reveal that the granodiorite has similar geochemical characteristics to I-type granites, while the monzogranite has compositions comparable to I-S transitional-type granites. The chemical variations of apatite zonations reveal that the magma reservoir of monzogranite was influenced by the melt component, heat and volatiles of mafic magmas, while the granodiorite magma reservoir is more likely to be affected by the heat and volatiles of the mafic magmas, and the participation of the mafic component is negligible. Combined with new regional studies, the Haisigou Triassic granitic intrusions might form accompanied with the slab break off at the late stage of the subduction of the Paleo-Tethys Ocea. In this context, the magmas in those reservoirs experienced crystal-melt segregations under the varying degrees of mafic magma recharge, and ultimately formed the monzogranite and granodiorite with cumulate affinities.