The invention discloses an adjustable drill support for decorating suspended ceilings. The adjustable drill support comprises a cross bar lever (1). The cross bar lever (1) is connected with both a fixed vertical pillar (3) and a long vertical bar (4). The fixed vertical pillar (3) is connected with the long vertical bar (4) through a connecting bar. The top end of the long vertical bar (4) is connected with an electric drill (5) through a strap (6). A metal pad (8) is disposed below the electric drill (5). The metal pad (8) sleeves a threaded bar (7) which is provided with a nut (9). During usage of the adjustable drill support, the part, exceeding the top end of the long vertical bar (4), of a drill pipe (10) of the electric drill refers to a deepest roof penetration distance; during advancing of the electric drill, when the upper end of the long vertical bar (4) contacts a suspended ceiling floor, the electric drill (5) gains the target depth and stops advancing.