The increasingly importance for the uses of the air lift pump in widespread list of fields (mining, nuclear industries, agricultural uses, petroleum industries...etc.) makes it very interested for the researchers to find tools to raise the performance outcome of such pumps. An air lift pump system was setup to study the effect of the suction pipe diameter and submergence ratio on the liquid (water) pumping rate. The system has a lift pipe of (0.021 m) diameter and (1.25 m) length. Five diameters for the suction pipe (0.021, 0.027, 0.033, 0.048 and 0.063 m) with a fixed length of (0.3 m), were tested for each of the submergence ratios (0.2, 0.3, 0.4, 0.5) respectively. Results indicate that the higher the diameter of suction pipe, the higher the pumping rate for a fixed submergence ratio. From another side, the higher the submergence ratio, the higher the pumping rate for a fixed suction pipe diameter. Also, under high submergence ratios, high pumping rates were achieved by the use of lower air flow rates compared with those used with lower submergence ratios. The experimental results show good compatibility with the model suggested by Stenning and Martin for the performance of an air lift pump.