i have problem to solve the error happened in my solidwork model. here i attach my CAD model to ask your help to fix it..thanks for your help. i very appreciate it.
One option is not using Freeform features. Some people like them, others hate them. I'm of the later group.
Notice the little sliver of a model face near the "top"? I'd eliminate it from the model, or at least from the freeform feature. It looks to be a three sided face/surface, so that means it terminates at a point. SolidWorks is often not fond of these surface points (aka singularity).
Instead of Freeform, the model face could be deleted and remade with a surface. It looks like you are using SW2011, so you won't have access to Boundary Surface, but the surface Loft, Sweep, and Fill command should do a decent job.
When working with the Freeform and surface commands, sometimes it can be a good idea to work on smaller portions. Instead of working on the entire face at once, break it (with Split Curves) into smaller chunks.
Keep an eye on your boundary conditions too. The Freeform feature lists Contact as its continuity type on every edge. This does not make sense though since many of the edges are formed by fillets. I think you'll want these to be Tangent instead.
Finally, add the fillets last. I think you'll have an easier time creating the Freeform or Surface to give the buckled look first and having it blend into the corners. Then you'll add the fillets and smooth things out. Having the fillets at the end allows for easier meshing with an FEA package too. If you have lots of little fillets with features (like surfaces and freeforms) dependent on them, it will be very difficult to delete or surpress the fillets later.
Someone will need to have SW2011 loaded to repair your model. If they fix it with a newer release, you'll only be able to import it without a feature tree.