Hello, the xy coordinate algorithm of cass latitude-longitude conversion is calculated in this way, which is divided into the following steps: 1. Open cass software, click data, and select coordinate change. 2. In the coordinate changing interface, select single point conversion, then set ellipsoid datum to select coordinate system, and select Beijing -54 coordinate system (or national -80 coordinate system). 3. Then enter the central warp of the original tape and the central warp of the new tape (0 reading, 0 minutes and 0 seconds). 4. Set the abscissa and constant to set the default value. 5. Next, enter the source coordinates. 6. Set the selection coordinate type and select geodetic coordinates. 7. Click on the coordinate transformation to output the target coordinates. 8. Obtain the latitude and longitude coordinates, with parameter b as the dimension coordinate and parameter l as the longitude coordinate. I hope it can help the subject!