Metal tube rotary flowmeter with characters of simple structure, wide measuring range, high reliability, using and maintenance conveniently, is widely applied in flow detection and process control. When the measured fluid is different from the calibrated fluid, the measured values is necessary to be corrected. The correction formulas of measuring value of metal tube rotary flowmeter were deduced, and the precautions for the correct installation of metal tube rotary flowmeter were described. It is pointed out that the correct and reliable measurement results can be obtained by applying the correction formulas and correct installation of metal tube rotary flowmeter.