Im really intrested in process of converting non parametric model (step) to parametric model . please provide links for tutorial

I think you're asking for two different tutorials:

1. If you want to convert the STEP file into a solid: Join all the surfaces together, and use the Close Surface to make the solid from the Join. (this solid will not be parametric)

2. My suggestion for adding the history back to a "dumb" STEP model (with no history) is to rebuild the model manually. This will provide the parameters for your parametric model. Take measurements off the "dumb" model to get the dimensions you need.

Typically, Boolean operations are not required for this.

To summarize my previous posts:

There is no easy, one-button solution to recapture the intelligence that was lost when the original file was translated (to STEP or other format).

With some manual effort, a new model could be created that contains the intelligence you want to define.

Thanks for the answer but how about models with complexity such filleted edges and smooth can we do that manually .moreover I am seeking for a technique like step file is imported and we draw over their surface to build feature after creating the model we just delete the step model in the tree is it possible?

For complex shapes; it is more difficult to copy and do manually. What is more important: parametric or accurate copy?

You could also create new "master" surfaces from the STEP file (using Extract and other tools), to create a "skeleton" to help define the parametric solid.

Method #1 (in my previous post) is using the STEP surfaces. After creating the solid, you can Isolate the solid and delete the STEP geometry.

I just did a project like this: STL to NURBS - Reverse Engineer Scan Data

As Jack said, there is no easy way to do it.

You need to define at the beginning what the goal is, and how you intend to use the data.
In my example, the new CAD model had to match the size and shape of the scan data. The model did not require parametric features to allow it's size or other attributes to be changed.

If the product is very complex, you might look at the Power Surfacing RE plugin for SolidWorks. It allows more complex, organic shapes to be created when working with scan, or otherwise imported data.
Obviously, that would lead to another expense, and the time needed to learn how to use the new program. I think they have a demo you can try.

Hi,
I've just launched a new course on PARAMETRIC DESIGN in CATIA.

https://www.udemy.com/catia-v5-parametric-design/

It's comprehensive course with multiple examples so if you are interested just give it a try.