It is important to study nonlinear dynamical systems showing pH and temperature oscillations simultaneously. Here, we systematically investigated the bromate sulfite reaction in its coupled system. Large-amplitude temperature oscillations could be measured accompanied by the pH oscillations with or without permanganate and manganese (II) ions. The modulation effects on the oscillatory dynamics of the bromate sulfite reaction system produced by permanganate and manganese(II) ions were investigated in detail. On the one hand, with permanganate, an additional negative pH feedback process between permanganate and bisulfite occurs, leading to weakening the pH positive feedback. The above opposite effects make the period length change unmonotonically when adjusting the permanganate concentration and flow rate. On the other hand, with Mn2+ as the feedback agent, the nonmonotonic change of period was not obvious because it only contained one feedback loop, which can only reinforce negative feedback without affecting positive feedback.