In this paper, taking overflow products of tailings cyclone in concentrator of Jiaojia gold deposit as main research object, hydration mechanism of fine tailings has been studied by using ordinary 425 cement (OPC) and self-made cementitious powder (KD) as cementitious materials. The main hydration products of OPC are Ca (OH) 2, calcium aluminate hydrate and a small amount of ettringite (AFT). The hydration products of KD are mainly ettringite and a small amount of calcium hydroxide. It is showed that the types of crystal hydration products of the two cementitious materials are obviously different. The cementation performance of KD material is better than that of OPC material, and the amount of KD in the test block is lower than that of OPC material to meet the same strength requirements. There are a lot of needle like ettringite filled between the pores of the particles in the KD consolidated body, which plays a bridging and supporting role in the structure. In the OPC consolidated body, the hydrated products, such as flaky Ca (OH) 2, CSH gel are not enough to completely fill the pores, and the "isolated island" structure is easy to appear in the structure, which has a negative effect on the strength.