Abstract: On-wafer testing system is necessary thru the whole design/ modeling and manufacture/ verification process of MMIC. Coplanar waveguide calibration chip is used to calibrate the microwave probe, since the reference plane is transferred from coaxial network analyzer to microwave probe. This paper designed and manufactured Al2 O3 based SOLT calibration substrate. The calibration chip is modeled. The load and short module's equivalent resistance and parasitic inductance in 1-40GHz has been analyzed, as well as the thru爷s group delay. The load resistance is about 45W, return loss is below -20dB between 1-30GHz, return loss is below -10dB between 30-40GHz. This paper demonstrates the validity of the whole SOLT calibration chip design, manufacture and calibration process.