Automatic detecting device and automatic detecting method for measuring precision of mechanical water meter

The invention discloses an automatic detecting device and an automatic detecting method for measuring precision of a mechanical water meter, which are used for locating a circle center of a plum blossom-like pointer of the water meter by using laser rays. The device is characterized in that an FPGA (Field Programmable Gate Array) processor is adopted for comprehensively controlling the detection process and processing test data; a CMOS (Complementary Metal-Oxide-Semiconductor Transistor) image sensor is adopted for converting a rotating signal of the plum blossom-like pointer of the mechanical water meter into a digital signal and outputting the digital signal to the FPGA processor for processing to obtain rotating turn number of the plum blossom-like pointer; two laser rays are adopted to automatically locate the circle center of the plum blossom-like pointer of the water meter; the two laser rays, the circle center of the plum blossom-like pointer and a pixel unit of the CMOS image sensor are located on the