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This problem is so weird,the normal map will make the surface shape. I had tried turn the Normal map to non-color and turn on shade smooth. However,they do not work.
$\begingroup$There are a few potential issues. If normal map was made for DirectX (most games) rather than OpenGL (Blender), you will want to invert the green channel of your normal map. If you have custom normals, they may or may not need to be cleared. If they were made for an app that triangulates differently, you may need to try alternative triangulation with a triangulate modifier. A file, with packed textures, would be necessary to help you troubleshoot-- but, your question is almost certainly dealt with elsewhere on the site, and you could probably get ideas about what to try.$\endgroup$
$\begingroup$Here is a related question to Nathan's comment: DirectX vs. OpenGL normal maps -- another thing you can try is to clear custom split normals (the button at the bottom right of the picture) that often cause shading problem for imported objects.$\endgroup$
non-color
and how is it plugged in your shader? $\endgroup$