Abstract: In this paper, five problems for branched system have been discussed: a) The characteristics of the dynamic matrix, characteristic matrix and the frequency eqution. B) The correction of Holzer method in determination of the solutions to the frequency eqution. C) The dynamic matrix and the characteristic matrix for straight-through-branched systems. D) Comparison between the method of the equivalent shaft and the method of the branched systems proposed by the author. E) Determination of the steady state solution in the system with forced torsional vibration for each branch and some opinions for raising the systemic dynamic stiffness.