The submitted paper reports a study of investigation of the dynamics of yarn tension, i.e. to the time dependence of the yarn tension on large-diameter circular knitting machines (LCKM). The special feature of this study is the fact that predictions are made for the course of the yarn tension during a single stitch-forming process.Only the yarn tension in the area of the yarn feeder and the yarn guide eye can be measured. Some results of such experimental investigations have already been published [1,2]. In this paper, additional results of theoretical model calculations are presented. In particular, by these calculations it will be possible to determine the structure of the yarn tensile force at the knitting point, i.e. in the region between knitting needles.The calculation of the yarn tension required a numerical solution of a system of non-linear differential equations. The special difficulty lies in the formulation of the non-equilibrium state of the running yarn, especially in the formulation of the robbing-back effect.