Abstract: In this paper,a new micromachined interdigital coplanar waveguide(CPW) structure has been developed and the transmission line parameters have been studied.For this interdigital CPW,the ground conductor is thickened by micromachining techniques which is helpful for reducing the interference between the adjacent parallel center conductors.Within the frequency range from 5 to 20GHz,the return loss of this structure has two minimal values whose positions change with the structural parameters.The relative bandwidths reached 23.5% and 9.97% at 8.3GHz and 16.55GHz respectively.The insertion losses are about 0.33dB/cm and 0.5dB/cm respectively.The interdigital CPW is useful for designing bandpass filter and phase shifter and minimizing the size of microelectromechanical system(MEMS) devices.