In this study, an experimental study was conducted on the performance characteristics of large-diameter submersible pumps with 400A and 1350A for drainage according to various flow rate changes. As a result, the total head of the submersible pump with a diameter of 400A decreased by approximately 36.28% from 5.43m to 3.46m, and the pump efficiency also decreased by 7.81% from 83.48% to 76.93%. As the discharge flow rate increased, the input power and the overall efficiency also tended to decrease. It was confirmed that the increase in the discharge flow rate decreased the total head and the input power, and thus the pump efficiency and the overall efficiency decreased. The total head of the submersible pump for the 1350A diameter decreased by about 34.4% from 4.36m to 2.86m, and the pump efficiency decreased by about 3.39% from 76.29% to 73.7%. As with the submersible pump with a diameter of 400A, the input power and overall efficiency tended to decrease as the discharge flow increased. As the diameter increased, the input power of the submersible pump was consumed more, and the total head, pump efficiency, and overall efficiency were lower.