The invention belongs to the technical field of compressors, and particularly relates to an oil pressure and air pressure monitoring device and method for a diaphragm compressor. Due to the fact thatthe diaphragm compressor is high in operational pressure ratio and large in pressure range, and the exhaust pressure can reach 300 MPa to the maximum extent; and if the method of machining pressure measuring holes in a cylinder body, not only is the cylinder strength affected, but also leakage can be caused, and potential safety hazards are brought. The oil pressure and air pressure monitoring device for the diaphragm compressor comprises a cylinder and a strain gage circuit, and the cylinder comprises a cylinder head; and the strain gage circuit comprises a strain gage assembly and a bridge circuit which are mutually connected, and the strain gage assembly is arranged on the cylinder head. The strain gage assembly is arranged on the cylinder head and connected with the bridge circuit, sothat the sensitivity of the strain gage assembly is improved, and the input and the output are in a linear relationship. The monitoring device is safe and reliable and has no damage to the diaphragm compressor, and especially under the high-pressure working condition, the hydraulic pressure in the oil-side cylinder head and the air pressure in the air-side cylinder head of the diaphragm compressorcan be monitored.