The utility model provides a mechanical sealing device used for granular media. A static seal ring and a rotating seal ring are arranged outside a rotating shaft in an opposite mode in the axial direction, and the axial end face of the static sealing ring and the opposite axial end face of the rotating sealing ring are sealing faces. The static seal ring is arranged on a fixing structure through an anti-rotation structure and springs, the springs are arranged along the circumference of the static seal ring at intervals, and the rotating seal ring is in transition connection with the rotating shaft or a shaft sleeve through a transmission structure. A flushing opening which is communicated with a flushing liquid supply source through a pipeline structure is formed in the sealing end face of the static seal ring. The sealing device is particularly suitable for sealing liquid media which contain solid particles and/or have the crystallization tendency characteristic, flushing liquid in the proper form is sent out through the flushing opening formed in the sealing end face of the static sealing ring to conduct flushing, therefore, the particles can be effectively prevented from gathering in the sealing end face of the static sealing ring, and crystals can be effectively prevented from appearing in the end faces.