Hi Lang, after loading your file it seems that your surface there is possibly not an actual cone, it's maybe some kind of slightly slanted thing? There is no "Cen" snap at the end so that probably means it's not exactly circular at the end and if it's not a symmetrical cone shape doing a circular array probably won't give you the right result.

If it's not an exact cone I'm not sure that any of the array tool will give you a proper result since most of them are oriented towards making a more uniform replication of an object and you will probably need a kind of non-uniform arrangement.

You may need to use the Flow command to map a flattened plane with objects on it onto your slanted surface.

Or were you intending that the piece that looks similar to a cone should actually be exactly conical and fully symmetrical? Because if that's the case you would probably want to reconstruct that piece to make it exact and if was an exact cone circular array would replicate things as you would need then.

- Michael