A probe cover for an ear thermometer includes a conical main body, an annular elastomer, a flange and a plurality of convex rib structures. The conical main body includes a closed end and an open end. The annular elastomer is connected with the open end of the conical main body. The flange is connected with the annular elastomer. The annular elastomer is arranged between the conical main body and the flange. The flange has a first surface and a second surface. The convex rib structures are disposed on the flange and spaced apart from each other, and the concave rib structures protrude upwardly from the first surface.