what is process for converting solid model into parametric model ?
It depends on the complexity of the model. Some cad systems have feature recognition capability and can do it on model import. I've seen mixed results that get worse as the model complexity increases.
Worst (or best, depending on how you look at it) case scenario is re-modeling from scratch, but you'll get the exact control you desire.
In CATIA using surface modeling tool, we can easily convert non-parametric model to parametric model. In GSD enough tool available to create the parametric model.