In this letter, a numerical short-open-calibration (SOC) technique is developed to be integrated with the electromagnetic (EM) software for direct de-embedding of propagation constant of substrate integrated waveguide (SIW). The two calibration standards, i.e., short- and open-end circuits can be perfectly built up by means of perfectly electric and magnetic walls in numerical algorithm. After three distinctive equivalent circuit networks are described for SOC de-embedding procedure, the complex propagation constants of SIW with respect to varied dimensions can be accurately de-embedded. Comparison between our extracted and those reported propagation constant is made to validate our SOC technique. In final, the phase and attenuation constants of SIW are derived to demonstrate the propagation and leakage characteristics of SIW.