Since this looks like a screen shot are you looking to get the screen smoother or your export? If to export go to the High Resolution Workshop in Composer and make sure your Anti-Aliasing is checked along with the High Resolution. This will get you the smooth edges you are looking for.
This pic is taken from - high resolution option only,
Parthi, Have a look at increasing the Refinement quality when you open the model into Composer. This will give you more triangles and a smoother surface. However, note that more triangles can result in slower graphics performance when moving items or rotating the scene.