hi guys..im new here,just wanna know what the advantage of inventor compare to the solidwork and autocad..anyone can help me?

AutoCAD is a general CAD tool, Inventor and Solidworks and mechanical 3D modelers.
 
Inventor is a tool from the makers of AutoCAD - so it works with true DWG format, and it also contains full AutoCAD. You can use not only parametric but also adaptive modelling. Inventor contains "functional design" tools - work with mechanical properties not geometric properties. In Inventor, there is an integrated document management system - Autodesk Vault, plus large standard part libraries.
Plus there are lots of add-on applications (both commercial and free), online libraries, discussion groups like this one -- and first of all users: Inventor sells more than any other 3D mechanical CAD software.

Agree, Inventor and Solidworks are nothing like Autocad, yes autocad is good at what it does, and the being 2d, in 2007 Autocad introduced it's all new 3d powers but  Inventor is years in advanced. The advantage go on and on too many to list, read up on parametric solid models.