Disclosed is a mechanical seal with an outer forwardly-inclined rim for liquids, including a moving ring and a stationary ring; end portions of the moving ring and the stationary ring are seal end faces in mutual friction and perpendicular to the axis, for preventing the liquid at one side of the seal end faces from leaking to the other side; one of the moving ring and the stationary ring is provided with a rim at one side in contact with liquid, and the rim is protruding in its radial direction and inclined toward the other ring, so that when a transmission device runs, liquid turbulence occurs to an inclined surface of the rim, and the generated centrifugal force makes particles or impurities in the liquid distant from the seal end faces, so as to effectively prevent particles or impurities in the liquid from entering the seal end faces.