Based on measurement of the load-depth curve in nanoindentation, the yield strength of thin metal film on Si substrate can be determined with the model of finite element analysis. An example is given of thin Cu film and the result shows that the yield strength thus determined can eventually reflect changes of processing condition both in deposition and in post-treatment. The yield strength and its variation can be explained in terms of grain orientation and grain size. (C) 2004 Kluwer Academic Publishers.