TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The air outlet connector extends in the hydrogen and oxygen producing machine. The air inlet connector is protruded from the water tank. The hydrogen and oxygen producing machine is connected with automatic water replenishing device and water tank air outlet tube. The automatic water replenishing device water groove top end is set with an exhaust port. The exhaust port is connected with an exhaust connector. The automatic water supply system mainly comprises an automatic water supply device, where the water tank and the hydrogen are connected with oxygen producing machine. The automatic water replenishing device water tank is set above the hydrogen and oxygen producing machine. The automatic water replenishing system father comprises a cooling device, which is connected with automatic replenishing water device on upper end. The cooling device contains space. The filtering tube body is set with multiple different inner diameters, and each filtering tube body is hollow in shape. Multiple different inner diameter of filtering tube body is sleeved in turn form step-shaped, and each one filtering tube body form a gap, the inner diameter of the smallest filtering one end tube body is connected with the exit containing space, and the other end with the cooling device, which is connected with the upper end of exhaust hole. The gas water mist of electrode group electrolysis hydrogen and oxygen producing machine electrolytic groove produce upward flow of liquid water in the automatic replenishing device water tank. The water liquid in the water tank is filtered in filtering device. The hydrogen gas containing water mist as water liquid enters automatic water replenishing device water tank after filtering impurity oxygen gas. The liquid water through multiple filtering tube body inside the automatic replenishment system enters filtering device and upward flow into the cooling device after flowing hydrogen and oxygen gas, the cooling device top end is contained with space, and flow path gap is set between filter tube bodies to effectively reduce the temperature of hydrogen gas. The filtering tube end of each hollow body of the top end or directly by the top end holding space extends downwards form filtering tube body of the containing space, and the other end is connected with the containing space. The cooling device through the bottom is set with the air inlet; the air inlet hole and the air outlet end are connected with the automatic water replenishing device. The hydrogen and oxygen producing machine by at least one fixing piece and the automatic water replenishing device combination fixed as a whole, the automatic water replenishing device is located right above the hydrogen and oxygen producing machine. The upper hydrogen and oxygen producing machine automatic water replenishing device is provided with aqueous solution is filled via the water tank tube at any time automatically and within hydrogen and oxygen producing electrolytic groove. The automatic water replenishing device water groove top end is set with through water inlet. The water inlet is connected with a water inlet connector.