In this study, gene expression programming (GEP), one of the Evolution Programming methods, is used for the control of the let-off system in a weaving loom. For this control, the function of warp tension occurring in a complete rotation of the main shaft of weaving loom is determined by the method of GEP. The control of let-off system is implemented using this function. Particularly, during the shed opening and beat-up processes to make warp tension constant, warp beam is rotated clockwise and counterclockwise. The values of warp tension obtained by GEP are compared with the values of conventional controlled methods. As a conclusion, the obtained warp tension values arc 11.2% less than values of classical approach. At the same time it is also provided that break rate of warp tension is decreased by 20%. It has shown that GEP is an effective tool for the decreasing of warp break rate.