To meet the urgent demand for green economic reactions in the production of polyether polyols, a new type of stirred reactor with horizontal baffles has been developed. Using computational fluid dynamics (CFD) numerical simulation, the effects of varying the channel size δ of the horizontal baffles, the baffle number n, and the inlet flow rate Q_A on the reactor flow field and residence time distribution (RTD) were studied. The results show that each impeller layer in the reactor can form an independent radial flow field, and the flow pattern in each chamber is the classic double circulation type. As δ decreases and n increases, the equivalent reactor number, N_eq, gradually increases. When Q_A increased from 0.011 m³/h to 5.65 m³/h, the normalized residence time θ remained stable, while N_eq gradually increased and the rate of increase decreased. Under the optimized conditions of δ=30 mm, n=3, Q_A=1.13 m³/h, the average residence time of the stirred reactor was 79.87 s, and N_eq was 4.19.