This differential pressure transmitter is designed for detecting micro differential pressure such as air or non-corrosive gas, etc. converting it into an electric signal for transmission. In addition, it is composed of a slack diaphragm, a range spring and a conversion circuit with differential inductance detector, therefore the displacement corresponding to the differential pressure caused on the diaphragm is converted into the quantity of electricity. It can be use for monitoring clogged filter, air duct flow speed and air flow in combination with pitot tube, and blower control application.