As an important part of the vanadium slag system, finding out the various characteristics of silicate minerals in the roasting stage will help to better grasp the evolution law of the vanadium slag system during the roasting process, and it is of great significance to guide the improvement of the roasting process. In this paper, the variation characteristics of main silicate minerals in the roasting stage of high calcium vanadium slag were analyzed through X-ray diffraction analyzer, mineral analyzer, scanning electron microscope and energy dispersive spectrometer. The results show that the temperature range of oxidative decomposition of fayalite is 334~850 ℃. At the initial stage of decomposition, amorphous quartz forms inside and outside the particles. With the increase of temperature, a gradually thickened iron oxide edge forms on the outer edge of fayalite particles until the particles are completely decomposed, and its decomposition products are quartz and iron oxide. The temperature range of oxidative decomposition of hedenbergite is 334~850 ℃, and the initial stage of decomposition is also marked by the formation of amorphous quartz inside and outside the particles. As the temperature rises, calcium vanadate ring and iron oxide appears on the outer edge of the hedenbergite particles until the particles are completely decomposed. And its decomposition products are mainly quartz, calcium vanadate and iron oxide. The reaction temperature range of dicalcium silicate is 640~850 ℃, and the initial stage of the reaction is marked by the presence of a calcium vanadate ring on the outer edge of the particles. With the increase of temperature, dicalcium silicate is gradually decomposed, and its decomposition products are mainly calcium vanadate, quartz and iron oxide.