A tunable optical oscillator based on a planar optical waveguide resonator was proposed. In this oscllator, the phase modulator is connected in series with the optical waveguide resonant cavity to replace the intensity modulator, the long fiber and the filter in the traditional system. Because the optical resonator is particularly sensitive to photon frequency and photon phase, by adjusting the laser wavelength, not only the intensity of the light can be adjusted, but also the frequency of the microwave photons can be selected. When the photon is resonant in the waveguide cavity, it will produce a strong delay characteristic, which can be used to replace the long fiber in the traditional system. The whole photoelectric oscillator system volume is long 29.5 cm, wide 21 cm, high 7 cm. In the experiment, each time to change the photon wavelength 0.1 pm, resulting in a 12.5~35.5 MHz step tuning effect, tuning range of 2 GHz. The system generates a 10 GHz microwave signal having a phase noise of －109.7 dBc/Hz@10 kHz at a center frequency of 10 GHz. Which provides a new idea for the miniaturization and practical application of the optical oscillator.