The study area is located in Arasbaran metallogenic zone. Rocks of the Sonajil region include Eocene andesite lava, porphyry microdiorite, Incheh granitoid and Ozuzdaghi Plioquaternary volcanic rocks. Porphyry microdiorite is the main host rock of porphyry type Cu- Mo mineralization in the Sonajil deposit. Much of the mineralization in the Sonajil deposit is dispersive and vein- veinlet type. Based on the structure, mineralogy and texture, the Sonajil vein- veinlets can be divided into sex different groups. These veins - veinlets contains sulfide (pyrite, chalcopyrite, molybdenite, bornite, galena, tetrahedrite, tenantite and enargite), hydroxide and oxide (magnetite and spicularite) and carbonate (malachite and azurite) minerals. Various types of fluid inclusions including mono-phase vapor, two-phase liquid and vapor, and multiphase liquid-vapor-solid of primary origin are present within quartz-sulfide veinlets.T_H (L-V) for halite-bearing inclusions homogenizing by disappearance of halite and of vapor are 260-565˚C, 320-520˚C, respectively and salinity are 35.3- 69 % NaCl. T_H (L-V) for two-phase inclusions homogenizing temperatures are 180-565˚C, and salinity are 0.7- 15.17 % NaCl. In bivariate plot of T_H-salinity, two distinct populations of high and low salinity fluids are recognizable and most of the data points relating to the high salinity plot above the halite saturation curve. The coexistence of vapor-rich two-phase and halite-bearing inclusions having similar TH ranges can be indicative of boiling in the Sonajil porphyry deposit.