The invention discloses a mechanical arm type ball outlet conveyor of a steel ball eddy current flaw detector. The mechanical arm type ball outlet conveyor is characterized in that the ball outlet conveyor is a three-section type conveyor, the three sections include the start end horizontal conveying section, the middle conveying section and the tail portion adjustable conveying section, a turnover box is placed at the lower end of the tail portion of the ball outlet conveyor, the ball outlet conveyor comprises a speed adjusting motor, a driving belt, a power wheel, a pressing wheel, a driven wheel and a conveyer belt, baffles are arranged on the two sides of the conveyer belt, grooves are formed in the inner sides of the baffles, the two edges of the conveyer belt slide in the grooves, a ball outlet is formed in the tail end of the tail portion adjustable conveying section of the conveyor, a proximity switch is arranged on the ball outlet, and a lead screw motor is arranged on the tail portion adjustable conveying section of the conveyor. The falling height of a ball is detected through the proximity switch on the ball outlet, the directions of the two rear sections of the ball outlet conveyor are changed by controlling the lead screw motor so that the falling height of the ball can be controlled within a certain range, and the finished product rate and the product quality of the steel ball are improved.