Abstract: For measuring solid-state microwave wafers such as GaAs, microwave probes are used to transform coplanar waveguide to coaxial reference plane. GaAs coplanar waveguide S-parameter standard for microwave calibration is discussed in this paper. The standard contains SOLT and TRL calibration module as well as matched transmission line, attenuation and VSWR verification cell. Balanced bridge structure is proposed in this paper, which can be due standards of VSWR and attenuation. Also, the in band characters are fine, and the artwork accommodation is also appropriate. After comparing with other calibration standards, the standard in this paper is demonstrated that the frequency covers 100 MHz ~50 GHz, VSWR covers 1.1,1.5,2.5,5,10, attenuation covers -1 dB,-2 dB,-3 dB,-10 dB,-20 dB,-30 dB,-40 dB, and the return loss of matched load is below -30 dB. Network analyzer calibration parameters are also extracted.