Rare lithium–beryllium metals are critical resources both nationally and globally. The United States, Australia and Japan have long listed Li-Be minerals among the raw materials prohibited for export, which only strengthens their strategic potential. In China, Li-Be mineral resources are not only abundant, they possess a superior metallogenic setting; however, their distribution is uneven and covered by substantial Quaternary deposits. In recent years, field research has gradually revealed an extent of granitic pegmatite lithium deposits in the Tianshuihai-Songpan-Ganze orogenic belt, capturing the attention of the domestic and international scholarly community. The prominent Zhawulong granitic pegmatite lithium deposit in Shiqu County, western Sichuan Province, lies in the middle part of this orogenic belt. Identifying the main controlling factors of lithium resource accumulation and the rules of rare metal enrichment for this deposit will provide a foundation and guidance for the next stage of strategic prospecting along the Tianshuihai-Songpan-Ganze orogenic belt. This paper presents a study on systematically sampled spodumene-albite pegmatite dike, muscovite-albite pegmatite, tourmaline-albite pegmatite dike, Kajiya two-mica granite pluton, fibrous tourmaline aplite, and staurolite-biotite schist from the pluton’s edge. LA-ICP-MS monazite U-Th-Pb isotope dating precisely identifies Zhawulong Kajiya two-mica granite’s formation date in the Late Triassic at 211–213 Ma, fibrous tourmaline aplite at c. 210 Ma, muscovite-albite pegmatite at c. 200–210 Ma, and Li-rich pegmatite at c. 205 Ma. Combined with previous geochronological data, analysis suggests a narrative of progressive formation from two-mica granite and fibrous tourmaline aplite to muscovite-albite pegmatite and spodumene-albite pegmatite. After 210 Ma, magma gradually entered the magma-hydrothermal stage, with an approximate 10 Ma period of continuous and multistage magmatic-hydrothermal activities. Combined with the trace characteristics of REE, K/Rb, Nb/Ta and Zr/Hf, which exhibit decreasing values from granite to pegmatites, and negative Nd and Eu anomalies in the monazite of highly evolved pegmatite, this study reveals the important role of granitic magma crystallization and differentiation in the process of rare metal enrichment for the Zhawulong deposit.