Abstract: In this paper, the Mn²⁺ and Br^- oscillating behaviour of the system were studied by using the E-t graphs, we find that both Mn²⁺, Br^- curves in the phase plane that can not be explained by limit cycle of two-dimensions.We used xy recorder, so that projections of limit cycles were got.The dimensions ofoscillating behaviour are not less than 3.We suggest the mechanism of reaction, and give a model as oregonator.