Tongchang and Fujiawu are two typical porphyry copper deposits in the Dexing ore field. Their metallogenic ages, metallogenic backgrounds and ore-forming porphyries are relatively consistent, but the Re contents of molybdenite in Tongchang are significantly higher than that in Fujiawu. In order to explore the effect of ore-forming fluid evolution on the heterogeneous enrichment of rhenium, LA-ICP-MS analysis on quartz and fluid inclusions in quartz in different metallogenic stages of Tongchang and Fujiawu were carried out in this paper. The results show that they have similar fluid evolution processes. The decrease of temperature, fluid boiling and the change of pH may be the main reasons for the precipitation of Cu and Mo. However, the temperature for the same metallogenic stage in Tongchang is lower than that in Fujiawu, and the fluid in Tongchang has higher salinity in the main metallogenic stage. Therefore, it is proposed that the temperature and salinity are the dominant factors leading to the heterogeneous enrichment of rhenium in molybdenite in the Dexing copper ore field.