The progress of electronics, radio engineering science, radio physics and communications advanced on improvements of physical, technological and circuit principles, methods and techniques of realization of any devices. One of many elements, which have interest for realizations miniature devices in microwave rang of frequency, is Сontrollable Micro-Strip transmission Line, made on Semiconductor Substrate (CMSLSS). This paper is about making model of CMSLSS, designing of software modulus for numerical simulation parameters and characteristics CMSLSS and receipt numerical results of this modeling. The structure of CMSLSS contain substrate of i-type semiconductor of GaAs, which have got fabricate active n-layer of GaAs on top-side, and the metallic strip of transmission line is located on active layer. This work may be useful for students and engineers who interesting of microwave semiconductors devices of AIIIBV group in which observe the Negative Differential Conductivity (NDC), or Negative Differential Resistance (NDR) effect.