We have found that La substitutions can improve the magnetic properties of the strontium ferrite films without reducing the saturation magnetization. In this work, SrCexFe12-xO19 nanocrystalline films (x=0, 0.2…0.8) with high coercivity were synthesized and deposited on SiO2 substrate by sol-gel method and sintering at 900 OC for 2h. The films were characterized by various experimental techniques including X-ray diffraction analysis (XRD), Field Emission Scanning Electron Microscope (FESEM), Vibrating Sample Magnetometry (VSM) and vector network analyzer. The results show that with the increasing content of cerium the coercivity of the films improves greatly and reach the maximum 6678.78 Oe at x=0.2, which is larger than La-doped strontium ferrite films, however the saturation magnetization decreases a lot. In the frequency range of 11.5-12 GHz the electromagnetic properties of the Ce-doped strontium ferrite films are better than La-doped at x=0.2.