The key indicator of electronic remote-reading water meter is mechanical-electric conversion. A non-real flow automatic test device for reliability of mechanical-electric conversion was developed based on digital image recognition. The article introduces the composition and working principle of the device, designs the mechanical positioning rotating mechanism of the device, and chooses Siemens S7-200 as the core of the lower controller. The soft platform chooses Delphi 7.0 to realize human-computer interaction and data storage.