Quartz vein-type tungsten deposits are the most important tungsten deposit type in the Nanling region of China. The Shanhu tungsten tin ore in northeastern Guangxi is a typical quartz vein-type tungsten-tin deposit, and there are still controversies regarding its mineralization age and fluid evolution mechanism. In-situ U-Pb dating and trace element analysis of wolframite, the most important ore mineral in the Shanhu tungsten tin ore, were conducted using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The mineralization age of wolframite is determined to be (100.5±3.0) Ma, which belongs to the late Early Cretaceous tungsten-tin mineralization event. This age is consistent with the emplacement time of the adjacent Yantianling granite (about 100 Ma), indicating that the mineralization is closely related to the regional Early Cretaceous granitic magmatic activity. The Y/Ho ratio of wolframite ranges from 5.04 to 8.30, and the Zr/Hf ratio ranges from 31.19 to 94.48, both deviating from the “charge-radius control” (CHARAC) range. The mineralizing fluid is characterized by a high F content, suggesting that F dominates the migration of tungsten through complexation. The δEu value of wolframite ranges from 1.14 to 1.85, showing a positive Eu anomaly, indicating that the mineralizing fluid was in a relatively oxidized environment during the mineralization process. The total rare earth element content in wolframite ranges from 10.54×10^-6 to 38.49×10^-6, and the Nb/Ta ratio is 0.02, which is significantly low, suggesting that the mineralizing fluid was far from the parent rock and underwent multi-stage evolution. In conclusion, the Shanhu tungsten tin ore is a product of late Early Cretaceous tungsten-tin mineralization and is genetically related to the magmatic activity that formed the Yantianling granitic body. The mineralizing fluid is a re-equilibrated magmatic water with characteristics of high F content, low pH, and high Eh.