Epitaxial Gd-doped CeO2（GDC） films grown on Y2O3？stabilised ZrO2（001） （YSZ） substrates by pulsed laser deposition （ PLD ） were investigated by transmission electron microscopy （ TEM ） and high-resolution transmission electron microscopy （ HRTEM） . Selected area diffraction （ SAD） patterns showed a cubic-on？cubic orientation relationship between the GDC films and the YSZ substrates. A semi-coherent interface with periodic misfit dislocations was revealed by HRTEM when imaged from 100 direction. The interface misfit dislocations at the interface were supposed to be the main mechanism for the strain relaxation of the interface . Two types of dislocations with Burgers vector b=1/2〈011〉 in GDC films were also revealed by HRTEM：one was pure edge dislocation and the other was a mixed type.