AllN thin films were deposited by the sputtering method. The effect of RF plasma cleaning on the AlN film crystal orientation was studied. The experimental results show that the AlN film c-axis orientation rocking curve was improved to 1.3° after cleaning with RF plasma for 3 minutes. The influence of Mo film substrate on AlN film crystal orientation was investigated. It shown that Mo thin film substrate with better orientation was beneficial for the growth of AlN film with c-axial orientation. The effect of Ar flow to AlN film stress was also analyzed, AlN film stress could be controlled from -390 MPa(compressive stress) to 73 MPa(tensile stress).