A diaphragm pump, comprising: a pump device, which includes a bladder and an electromechanical member; at least two cavities formed in the bladder and a shaft of the electromechanical member connected to the bladder for driving the cavities to move upward and downward so that the cavities are further compressed or expanded; a pump body, which includes at least two air inlet passages, at least one air outlet passage and at least one leak-proof passage; the air inlet passages, the air outlet passage and the leak-proof passage selectively communicating with one of the cavities; a top cover connected to the pump body and provided with a valve port, an air vent and an air outlet duct; and an air release valve head mated to the valve port in a separable manner; air pressure in the leak-proof passage acting on the air release valve head so that the valve port is closed by the air release valve head while the pump device pumping air; the air release valve head and the valve port separated from each other when the pump device stops pumping air; wherein the pump body further includes a first valve seat and a second valve seat; wherein the air outlet passage consists of a first air outlet channel formed on the first valve seat and a second air outlet channel formed on the second valve seat while the leak-proof passage includes a first leak-proof channel formed on the first valve seat and a second leak-proof channel formed o the second valve seat; wherein a first valve membrane is located between the first valve seat and the second valve seat and is provided with a leak-proof valve plate and an air outlet valve plate; the leak-proof valve plate being mated to an outlet of the second leak-proof channel in a separable manner while the air outlet valve plate is arranged at an outlet of the second air outlet channel in a separable manner; the first leak-proof channel and the first air outlet channel being able to communicate with each other or not communicating with each other; wherein a second valve membrane is arranged between the top cover and the first valve seat; a pressure chamber communicating with the leak-proof passage is defined and formed between one side of the second valve membrane and the first valve seat while an air outlet chamber is defined and formed between the other side of the second valve membrane and the top cover; the air release valve head being integrally formed on the second valve membrane; characterized in that a first boss used for supporting the air release valve head is disposed on the first valve seat and a surface of the first boss is recessed to form a first indentation. a pump device, which includes a bladder and an electromechanical member; at least two cavities formed in the bladder and a shaft of the electromechanical member connected to the bladder for driving the cavities to move upward and downward so that the cavities are further compressed or expanded; a pump body, which includes at least two air inlet passages, at least one air outlet passage and at least one leak-proof passage; the air inlet passages, the air outlet passage and the leak-proof passage selectively communicating with one of the cavities; a top cover connected to the pump body and provided with a valve port, an air vent and an air outlet duct; and an air release valve head mated to the valve port in a separable manner; air pressure in the leak-proof passage acting on the air release valve head so that the valve port is closed by the air release valve head while the pump device pumping air; the air release valve head and the valve port separated from each other when the pump device stops pumping air; wherein the pump body further includes a first valve seat and a second valve seat; wherein the air outlet passage consists of a first air outlet channel formed on the first valve seat and a second air outlet channel formed on the second valve seat while the leak-proof passage includes a first leak-proof channel formed on the first valve seat and a second leak-proof channel formed o the second valve seat; wherein a first valve membrane is located between the first valve seat and the second valve seat and is provided with a leak-proof valve plate and an air outlet valve plate; the leak-proof valve plate being mated to an outlet of the second leak-proof channel in a separable manner while the air outlet valve plate is arranged at an outlet of the second air outlet channel in a separable manner; the first leak-proof channel and the first air outlet channel being able to communicate with each other or not communicating with each other; wherein a second valve membrane is arranged between the top cover and the first valve seat; a pressure chamber communicating with the leak-proof passage is defined and formed between one side of the second valve membrane and the first valve seat while an air outlet chamber is defined and formed between the other side of the second valve membrane and the top cover; the air release valve head being integrally formed on the second valve membrane; characterized in that a first boss used for supporting the air release valve head is disposed on the first valve seat and a surface of the first boss is recessed to form a first indentation.