This paper studies the behavior of the giant swing motions of a 3-link horizontal bar gymnastic robot using the delayed feedback control (DFC). A modified DFC method called Multiple-prediction Delayed Feedback Control (MDFC), which controls the chaotic system via periodic gain is proposed in this paper. First, plural Poincaré maps are defined to regard the target continuous-time system as a T-periodic discrete-time system, so that the system stability can be evaluated based on the theory of monodromy matrix. Second, a way to calculate analytically the error transfer matrix and the input matrix which are necessary for discretization is presented. Finally, simulation results show that our proposed method is effective in the control of the giant swing motions.