A racetrack waveguide resonator filter was fabricated on K9 glass by ion-exchange in mixed melt salt of AgNO3 and KNO3. The free spectral range of the filter was 0.178 nm, and the contrast of the two output ports were 1.47dB and 6.5 dB, respectively. From the measurement parameters, the splitting ratio of the coupler and propagation loss of the resonator were analyzed to be 0.16 and 8.1 dB/cm. The phase shift of 2π was realized by using thermo-optical effect within 16 ℃ temperature change, and the thermo-optical coefficient of the waveguide material was about 1.28×10-5 /℃.