RFC 7946 warning: non-WGS84 GeoJSON output.

[ABCBeacuse]

I had a problem converting the Shp file to GeoJSON，
Can you give me an command to fix it ？

[mbloch]

GeoJSON files usually use the WGS84 coordinate system, which has coordinates in degrees of latitude and longitude. It looks like you have a "projected" Shapefile, which uses a different kind of coordinate system. You can try this:

mapshaper input.shp -proj wgs84 -o output.geojson