In two symmetrical working cavities of diaphragm pump. Each of them is equipped with an elastic diaphragm 6. The connecting rod forms the two diaphragms into a whole. After the air inlet connector 1 of the small compressed air pump enters the air distribution valve 3, it pushes the diaphragms in the two working cavities. It drives the two diaphragms connected by the connecting rod to move synchronously. meanwhile. The gas in the other working chamber is discharged from the back of the diaphragm. Once you reach the end of your journey. The valve mechanism will automatically introduce compressed air into another working chamber and push the diaphragm to move in the opposite direction, thus forming the synchronous reciprocating motion of the two diaphragms. Each working chamber is equipped with two one-way ball valves 4. The reciprocating motion of the diaphragm changes the volume of the working chamber and forces the two one-way ball valves to open and close alternately. Thus, the liquid is continuously inhaled and discharged.