AutoCAD conversion in .stp format or catia.....is it possible.....
3 Answers

Yess, I, myself do it using INVENTOR FUSION that comes with the AutoCAD installation disk (otherwise you can download it from Autodesk for FREE)... Just open .dwg in the Fusion and Save As .step/.stp, whatever you like... You can open .step in CATIA...
Enjoy... :)

You can convert your autocad file in .CATPart with CrossManager : http://www.datakit.com/cad-convertors/dwg-dxf-3d-to-catia-v5-3d/15-2-0.html