Terahertz (THz) band is an important range in photonics, and provides numerous advantages in various applications. One of the most popular detection methods for THz pulses is electro-optic sampling (EOS). EOS provides many benefits; however, in this method distortion damages the output signal, and limits the bandwidth of this technique. In this article, a calculation-based approach is proposed to remove the effect of distortion in EOS detection process. This manner is based on definition of a base-level spectrum which modifies the output of EOS to eliminate unwanted disorders. The introduced method is computational, inexpensive, feasible, fast, adaptable, and effective. Moreover, a detailed comprehensive step-by-step model of THz time-domain spectroscopy (THz-TDS) with a simple and obvious perspective for ZnTe and GaP crystals is provided.