The Longshan Complex located in the Qinling-Qilian junction zone is the key to understanding the tectonic evolution of this junction. This study conducted petrographic observations, phase equilibrium modeling and monazite U-Pb dating, to better discuss the tectonic implication. Based on petrographical observation and mineral composition analysis, the garnet biotite plagioclase gneisses sample 21LS30-1 of the Longshan Complex display two metamorphic mineral assemblages: the prograde stage (M₁) (biotite + plagioclase + quartz + rutile + ilmenite) and the peak stage (M₂) (biotite + garnet + plagioclase + quartz + rutile + ilmenite + melt). Sample 21LS37 exhibits two sets of metamorphic minerals during different formation stages: the prograde stage (M₁) (biotite+sillimanite+plagioclase+quartz) and the peak stage (M₂) (biotite+sillimanite+garnet+K-feldspar+plagioclase+quartz+ilmenite+melt). Phase equilibrium modeling constrained the peak p-t conditions of the two samples to be 813~821℃, 1.08~1.1 GPa and 815~819℃, 0.93~0.97 GPa, reaching the medium-pressure granulites facies metamorphism. LA-ICP-MS monazite data from the garnet biotite plagioclase gneisses show ²⁰⁶Pb/²³⁸U ages of 451~425 Ma, 455~431 Ma, 415~395 Ma and 415~394 Ma, respectively. The Longshan Complex and the North Qinling Orogenic Belt underwent similar tectonic processes during the Paleozoic. We preliminarily proposed that the Longshan Complex belongs to the western extension of the North Qinling orogenic belt and has experienced Paleozoic continental-continental collisional orogeny.