I need this sheep modeled which software is best?

Use blander software to create this type of model

That puffy wool texture is going to be the biggest hurdle for mechanical CAD programs like SOLIDWORKS and Inventor.

An organic modeler like Z-brush, Mudbox, Cinema 4D, or Blender may be a better option, but it really depends on what you plan to to with the CAD data.

Another option is to capture the existing model via laser scanning, or Photogrammetry. Again, it really depends on what the final goal is. Some 3D data is not suitable for some goals.

Can any one make box shape cut from top side of sheep in this model.
Thanks

I agree with FredSWUG, SolidWorks is perfect for mechanical designing. But when it comes to organic modelling, it is pretty lame.
I made a similar model a couple of months ago (Shaun the Sheep) in SolidWorks, spending - roughly - eleven continuous hours designing its 74 features!
Choose wisely... AutoDesk Inventor and SolidWorks have many common features. Unless you're a pro "deform"er, don't use Inventor.

I suggest Blender, Meshmixer & SculptGL as they are free. If paying isn't an issue, then try ZBrush, Mudbox or Modo.