Abstract: Based on the fracture problem of nylon rods in the middle of shaft coupling due to the movement of gas extraction pump and other devices caused by mechanical vibration, the cavitation of gas extraction pump and water hammer vibration, we analyzed the main influence factors, combined with SEW reducer installation accuracy, we detect coaxially of shaft coupling among three kinds of devices of pumps, reducer, motor by dial indicator axis and radial method and measure its displacement and slope of two axis, and determine the coaxially deviation adjustment quantity and equipment base leveling method by using similar triangles calculation method, which provides a simple detecting and adjusting method for the regular detecting of the gas extraction pump.