[Sheyko]

I try to smooth surface mesh up to 0.2 quality value, however it doesn't work.
I suppose the "smoother" should divide the bed elements on some smaller but it simply change a little bit the mesh angle.
The Repair Mesh->Remesh Bed Elements also doesn't give me any results.

[PSYMN]

Right click on the mesh branch of the tree and display the nodes "as dots". My guess is that you will find that the nodes in this area are each projected to a specific point... This over-constrains the mesh and does not leave the smoother free to move the nodes.

Ideally, you should remove all points that you don't want to constrain nodes before you mesh. But after meshing you can still adjust the association for individual nodes. For instance, perhaps only the very corner nodes should be projected to a point and the others could be surface or curve projected (allowing them to be moved by the smoother).

[Sheyko]

Thanks Simon,

It is true on the line inflections; however it should be also another ways. For the instance condense the mesh in worse quality regions or move the nodes close to short edges, how do so?

[PSYMN]

refine or coarsen mesh are shown as check box options under the smoothing setup... You could also refine with the edit mesh tools before smoothing. If the smoother has more nodes that are flexible, it can do more.

But fix your over constrained geometry first.