-A tuning algorithm of linear controllers P, PI, PID in multiple-loop feedback control systems is proposed in this paper. The control objects consist of three subprocesses, which are described by dynamical models with inertia (third order). The controllers in the internal contours 1 and 2 and in the external contour are tuning according the maximal stability degree method. In the internal contour is used controllers P and PI, in the external contour is used controllers P, PI, PID. There are using the iterative procedure, for determinate the optimal parameters of controllers P, PI, PID. The tuning algorithm of controllers represents an algebraic method, which consists of two stages. On first stage the numerical value of the optimum stability degree of designed control system is determined. On the second stage the numerical value of tuning dynamic parameters of controllers are determined from algebraic expressions.