This paper studies the interfacial delamination resistance for weak interface between piezoelectric PZT and metallic Cr thin films deposited on silicon substrate. An experimental technique using sandwiched cantilever type specimen was developed to measure the mechanical strength of the interface in thin film structures. To understand the experimental data obtained, we proposed two delamination criteria for crack initiation that are based on stress intensity concept and cohesive zone model, which accordingly provided two parameters that describe the resistance to the interfacial delamination, i.e., stress intensity factor K-d and the work of interface separation per unit area Gamma(0) , respectively.