In a brake control method of a power wheelchair, the power wheelchair includes an electronic gradienter, a brake sensor, a brake apparatus, and a brake controller. The electronic gradienter detects stability data of the power wheelchair to obtain a gradient angle and a gradient direction of the power wheelchair. When the gradient angle does not exceed a safety angle range, the brake controller controls the brake apparatus to brake the power wheelchair, and the brake sensor detects braking data of the power wheelchair. The method calculates a braking strength value for braking each wheel of the power wheelchair according to the gradient angle and the gradient direction of the power wheelchair when the brake operation on the power wheelchair is improper. The brake controller adjusts the brake apparatus to brake the power wheelchair according to the braking strength value of each of the wheels.
