In this paper, a interdigital bandpass filter from 1 GHz to 1.41 GHz and another one from 1.41 GHz to 2 GHz are designed. They were from lumped low-pass structure transformation to interdigital microstrip line structure by classical design method, so as to solve the problems that complex structure, narrow bandwidth and huge insertion loss of lumped structure filter in high frequency. Based on ADS and VNA, the filters had been simulated and optimized and the response of S21 had been measured. Final results show that achieve index requirements.