A small unbalanced magnetron atom source with multipole cusp magnetic field anode is described. The co-axial magnetron principle is extended to the circular planar magnetron atom source, which raises the efficiency of sputtering target area up to 60 %. The multipole magnetic field is put in the anode, which makes the unbalanced magnetron atom source run in a higher discharge current at a lower arc voltage condition. Meanwhile, the sputtering atoms through out the anode can be ionized partially, because the electron reaching the anode have to suffer multiple collisions in order to advance across the multipole magnetic field lines in the anode, which enhances the chemical reactivity of the ejecting atoms in film growth and improve the property of film depositing.