Dual-band bandpass filter using stub-loaded resonators (SLR) based on GaN MMIC is presented in this paper. The proposed circuit consists of two symmetric stub-loaded resonators, which are folded and coupled to each other. The two passband frequencies can be eas- ily controlled by tuning the length of the half-wavelength resonators and the open stubs shunted at the midpoint of the microstrip lines. Moreover, the ports are directly tapped at the resonators. And additional open stubs are added to the 50-ohm feed lines for better performance. Benefit- ting from the integrated circuit technology, the filter can be designed on GaN MMIC that only occupies a small size. For demonstration, a filter, centered at 40 GHz and 60 GHz, is designed and the simulated result shows good performance.