In order to meet the miniaturization requirements of a certain filter in satellite communications, a C-band interdigital filter with a ceramic substrate was designed based on thin film technology. The filter is composed of a 5-order parallel coupled resonant unit, and the input and output form adopted a tap structure, which is more conducive to the miniaturization of the filter than the parallel coupling input and output. In order to meet the high rejection index, the filter adopted cross-coupling and parallel 1/4 wavelength open route to introduce transmission zero points, which effectively improved the filter’s out-of-band rejection.Besides,the standing wave of the filter was adjusted by means of impedance compensation.The test results showed that the center frequency of the filter is 3.7GHz, the relative bandwidth is 27%, the center insertion loss is -1dB, the stopband rejection is 30dB at 2.7GHz and 4.8GHz, and the stopband rejection is 40dB at 2.5GHz and 5GHz. The filter size is 9.25mm *6.72mm.