Using wavelet and harmonic methods, he paper has developed a new approach for PEMFC gas starvation diagnosis. By a self-designed 3D diagnostic PEMFC distributed parameter model, the research established a model-based diagnostic method, which is more simple and economical compared with experiment methods. Further, based on the model and its UDF (user-defined functions), the typical faults of gas starvations in anode, cathode and both side, and the dynamic boundary conditions have been embedded. Under the different faults, the simulation experiments of PEMFC were carried out. Another benefit for the research is that the diagnostic method is only based on the output stack voltages. By using two different methods of wavelet analysis (Morlet and Daubechies) and harmonic analysis (mainly using the Total Harmonic Distortion Analysis, THDA) respectively, the gas starvation faults in anode, cathode and both side are recognized and distinguished successfully.