This study aimed to examine the pozzolanic reactivity and hydration products of cementitious materials prepared using molybdenum tailings. During the grinding process, the particle size of molybdenum tailings decreases continuously between 15 and 60 min, and the specific surface area increases from 367 to 932.4 m2/kg. For this, samples were prepared using 91 wt% milled molybdenum tailings, 3 wt% natural gypsum, 6 wt% calcium hydroxide, and a mixture of 0.3 wt% water reducer and water:binder at a ratio of 0.2. The phase transformation and hydration products of molybdenum tailings were analyzed using a compressive strength tester, X-ray diffraction, scanning electron microscopy, and infrared radiation. The 3-, 7-, and 28-day compressive strengths of the samples were found to be 1.67, 3.17, and 3.83 MPa, respectively, which shows that the molybdenum tailings have pozzolanic reactivity. Other testing means showed that the molybdenum tailings are mainly composed of ettringite and C-S-H gel under standard curing conditions, and the collaborative generation process of ettringite and C-S-H gel may exist in this system.