The electroless Ni-P/Ni-W-P duplex coatings were deposited directly on 7075 aluminium alloy. The morphology of surface and cross-section, composition, structure, microhardness and corrosion properties of coating before and after heat treating were studied by SEM,EPMA,XRD, microhardness tester, electrochemical workstation. The result shows that amorphousNi-P/Ni-W-P duplex coatings with good adhesion between interfaces and the substrate fully covered without pores are got.The hardness is improved and corrosion properties are a little decreased after heat treatment.