how to extract a DEM using the polygon?

[KeWang1]

I have the whole world DEM and a country's shapefile, how can I only get this country's DEM in Pro? Which tool to use? Intersect? Thanks

[JakeSkinner]

Hi Ke,

You will need the Spatial Analyst extension, and then you can use the Extract by Mask tool. 

[DanPatterson_Retired]

And if you intend to do any projection during or after the extraction process, make sure you read up on 

How the Cell Size Projection Method environment setting works—Geoprocessing | ArcGIS Desktop 

so that your data maintains some semblance of the original.  If you are working with a raster and featureclass in decimal degrees, then the raster extent and cell size are the only things you need to consider.  If you intend to project the raster then the projection method will be a factor