Geothermal fluid geochemistry along active fault is a powerful tool for studying coupling of mantle-derived and crust-derived fluid. Four hot springs along Minjiang fault were investigated systematically for seven times(from June 2010 to July 2018). The helium and carbon isotope(³He/⁴He, δ¹³C_CO2) and gas compositions of 16 gas samples and major and trace element composition and stable isotope values(δ¹⁸O、δD) of 27 water samples were measured. The results show that:①there are mainly four hydro-chemical types:Ca-HCO₃、Mg-HCO₃、Ca·Mg-HCO₃ and Mg·Ca-HCO₃ of the thermal springs in the Minjiang fault zone. ②δD and δ¹⁸O values(-13.2‰~-19.8‰ and-95.6‰~-113.33‰) of the geothermal waters indicated that the hot springs were with a meteoric origin, where the recharge elevation range is at 3436~4506m. ③SiO₂ in the region is 2.49~5.92mg/L, and thermal storage temperature estimated by aqueous geothermometry was 26.00℃~52.22℃. This data, along with estimated temperature, gave an estimated circulation depth for the spring waters of 1.17~2.67km. ④the Na-K-Mg triangle diagram indicates that the spring water was a type of immature water. ⑤almost all trace element concentration coefficients are less than 1 except for B、Sr and Ba in the spring water of the Minjiang fault zone, which suggested that the contents of trace element were low, and with a limestone origin. ⑥the He-C and He-Sr systematics were mostly controlled by the mixture between mantle and various crustal sources. The observed ³He/⁴He ratios varied from 0.02 to 0.68Ra(Ra is atmospheric ³He/⁴He ratio=1.39×10^-6) indicated that hot springs discharge gas with a low contribution of mantle-derived helium. The limestone was the primary source of carbon(75%~99.47% of the total carbon inventory) from the hot springs in the Minjiang fault zone. It was found that the geochemical characteristic of hot spring fluids before and after the earthquake has changed obviously. But the observed ³He/⁴He ratio indicates that hot springs discharge gas with a low contribution of mantle helium. Based on above observation, a fluid geochemistry model was proposed for the geochemical system combined with the geology and hydrogeology of the study area, it is very significant for the determination of precursory anomalies of the future medium-strong earthquake along Minjiang fault zone.