LA-ICP-MS (Laser ablation-inductively coupled plasma-mass spectrometry) analysis of fluid inclusion is characterized by high precision, low detection limit and simultaneous measurement of multiple elements, which has remarkable advantages in revealing the specific mineralization processes. Based on using synthetic NaCl-H2O-Rb-Cs and NaCl-KC1-CaCl2-H2O-Rb-Cs fluid inclusions in quartz, a reliable analytical method of quantitatively determing major and trace elements in single fluid inclusion by LA-ICP-MS was established. In this method, external standard NIST610 and internal standard Na were used. The Na content was obtained from microthermometric measurement and calculated using the charge-balancing method. Analytical results show that the accuracy is within 16% and the precision is better than 7% RSD. In addition, combined with using the external standard NIST610 and a natural quartz standard, an analytical method for determing trace elements in quartz was also established. The accuracy for Li, Al and Ti is within 10% and the precision is better than 5% RSD. The above methods were applied to study the Cu and Mo mineralization mechanisms in the Wangjiazhuang Cu-Mo deposit in Luxi Block, eastern North China Craton. The results show that Cu is enriched in vapor-rich fluid inclusions, whereas Mo is concentrated in daughter mineral-bearing fluid inclusions, indicating that Cu was prone to be carried by vapor while Mo was likely carried by brine. This property is thus likely responsible for the depositional separation of Cu and Mo in the deposit. In addition, from the magmatic quartz to the ore-forming and then to the post-ore-forming quartz, the Ti contents decrease while the Al contents increase, suggesting the precipitation of Cu and Mo was also affected by the temperature and pH changes of the fluid.