Abstract: Ag/Cu double-layer film was doposited on internal wall of coupled cavity by magnetron sputtering process, and the electrical performance of the film and the film-substrate adhesion strength were studied.The results show that the adhesion strength between the double film and the substrate up to 5.0 MPa. The coupled cavity with 2 μm Cu/2 μm Ag has the best eletrical performance, its coupling-degree was between 5.75 dB and 6.20 dB, isolation and port standing wave were 31.02 dB and 24.43 dB,respectively, these parameters were all up to the electroplating standard. Insertion losses of the coupled cavity was less than 1.70 dB, completely better than the electroplating standard. The process of low Ag coating costs and non-polluting could be used as an alternative method for the plating process.