SOXS (Son Of X-Shooter) is a new spectrograph for the ESO NTT telescope, currently in the final design phase. The main instrument goal is to allow the characterization of transient sources based on alerts. It will cover from near-infrared to visible bands with a spectral resolution of R similar to 4500 using two separate, wavelength-optimized spectrographs. A visible camera, primarily intended for target acquisition and secondary guiding, will also provide a scientific "light" imaging mode. In this paper we present the current status of the design of the SOXS instrument control software, which is in charge of controlling all instrument functions and detectors, coordinating the execution of exposures, and implementing all observation, calibration and maintenance procedures. Given the extensive experience of the SOXS consortium in the development of instruments for the VLT, we decided to base the design of the Control System on the same standards, both for hardware and software control. We illustrate the control network, the instrument functions and detectors to be controlled, the overall design of SOXS Instrument Software (INS) and its main components. Then, we provide details about the control software for the most SOXS-specific features: control of the COTS-based imaging camera, the flexures compensation system and secondary guiding.