This paper makes a systematical geochemical analysis on the Dahu molybdenum gold deposit in Xiaoqinling Area. The main gas compositions of the fluid inclusion are CO2 、H2O and a little of reducing gas，such as CH4 and C2H2. The main liquid components are Na+，Ca2+，Cl-、F-，etc. Hydrogen and Oxygen isotope display ore forming fluid of molybdenum and gold deposit were mainly from magma water，but the Hydrogen and Oxygen isotope of the kinds of ore bodies also show some differences. Rare earth compositions of the molybdenumization quartz vein and potash feldspathization、pyritization quartz vein have obvious differences，molybdenumization quartz vein has higher ∑REE and LREE—HREE fractionation，the ore forming fluid source of gold and molybdenum may be different，molybdenum and gold ore bodies maybe formed in different period.