In this paper we obtained new approach for the problem, which it is described in reference[1,2]. In the references [1], the authors are studied Decomposition of Linear-Quadratic optimal Control problems for Two-Steps Systems. In [1], the authors assumed the switching point is fixed and it is given algorithm for solving Linear-Quadratic optimal Control problem. But in presented paper author assumed more general case, in the case of switching point is unknown and by using transformation, it is reduced to the problem which is defined in the ref. [1,2]. The unknown switching point case is more practical than the case of known switching point