A sheet cutting and bending apparatus for cutting a wavy sheet and forming trapezoidal notches required for installation includes a base, two cutters at an end of the base, and a force applying mechanism for driving the two cutters. A knife of the cutters has no handle but just has a curved force receiving edge at the rear edge. The force applying mechanism has two rocker aims driven by a rocker rod and a force applying rod bridging between the two rocker arms for abutting a force receiving edge of the knife to produce a shear force and pushing the knife efficiently to cut two incisions at an edge of the sheet. In addition, a bending mechanism is linked with the force applying mechanism and provided for flipping a plate between the two incisions inwardly to form trapezoidal notches required for installation at the edge of the sheet.