Subtract one from the other mesh?
Or without 3d max can not do?

What’s the question? Subtract one from the other mesh doesn’t say a thing.. One Vertex? one Face? one submesh? which is the ‘other mesh’.. which is the mesh it is the other one from?

It would be helpful if you remember to state the full question. I’m guessing from the name that English might not be a native language but try to explain the issue as best as you can.

3D Max is a modelling program.. I can think of plenty of others which are.. in my view better. some aren’t as easy to use, some are limiting, but they are normally much cheaper for a start, and when you can get the hang of them, are pretty easy.. apart from the native format (which is a real pain.. why does anyone else .max anyway) I can’t see any reason for 3D max over any other program..

Exempl code:
***
var p1:Mesh=new Mesh(new CubeGeometry(());
var p2:Mesh=new Mesh(new CylinderGeometry(());
***
Objective: To remove the volume occupied by p2 from n1 ,or another  a circular opening in the cube to make.

While totally possible, there is no implementation of a Booleans/CSG class in Away3D.

would be a pain of creating new vertex points and faces.. a standard cube has only 2 faces per side.. depending on the cylinder, it would have to create a lot of new points and faces.. while I can see SOME reasons for doing this.. personally.. I would just have 3 models.. a cube, a cylinder and a merged one.. that is, if I was doing a game where for some reason, you needed to make a large hole in a cube.

It is much easier to organize the export of 3DS model, made by a third-party editor.

It’s not a question of easy or difficult.
Keep in mind that while most choose to export fully defined models from their editor because creating dynamic requires more work/effort and knowledge. There are plenty plus points associated with runtime generation. Such as file size/fast loading, adaptive resolution depending on device etc..
The booleans operation in particular do save a lot on geometry side.

This wish developers Away 3d ,or there is a real possibility of Boolean operations in 3d primitives?

There is no plans for the dev of such feature/tool.

not very great.. but what about masking?