An interdigital micromechanical filter for Kband is designed in the view of requirements for the millimeter waveband of 5G wireless communication systems. The filter adopts the tapped input and output, and the input and output signals are led to the uppermost metal layer through the metal holes of the upper dielectric layer, and combined with the cavity design of the upper and lower dielectric layers, thereby effectively reducing the size of the filter. The enclosed doublelayer structure can effectively shield the external electromagnetic environment from interference with its internal structure. The filter structure is simulated and optimized by using software such as HFSS. The final target requirements of center frequency of 25.875 GHz, passband insertion loss of less than 2.5 dB and relative bandwidth of 12.56% have been satisfied. The final design size of the filter is 5.098 mm×1.873 mm×0827 mm. The miniaturized design is realized while the highend outofband rejection is good.