how to copy a part of design

Yes, it is and you have 2 options:

1. Use Export->Clipboard feature

2. Use replicate modules available in Placement Mode

Thank you for your reply.

Regarding the 1st option, there is no clipboard feature in export tab. How can I enable it?

Regarding your 2nd option, Could you please clarify it?  where can i find replicate modules?

Try Export->Sub-Drawing, looks like you have a different GUI (it happens due to Licensing and version)

On #2 you need a minimum OrCAD professional License to do this (note: it might be different on yourGUI),

In the original design, enter placement mode:

This will allow you to select Symbols without being in a command

Select the group you'd like to replicate and right click on it and select Place Replicate Create

Select additional items like traces/shapes/vias, right click Done and select origin. Save it as a module when prompted

In the Destination, enter the placement mode, select the components you'd like to apply this to and right click, selecting Place Replicate Apply and the module name.

Eventually, break the module by selecting Groups from the filter in place mode, select the group, right click and then Disband Group.

On #2 you need a minimum OrCAD professional License to do this (note: it might be different on yourGUI),

In the original design, enter placement mode:

This will allow you to select Symbols without being in a command

Select the group you'd like to replicate and right click on it and select Place Replicate Create

Select additional items like traces/shapes/vias, right click Done and select origin. Save it as a module when prompted

In the Destination, enter the placement mode, select the components you'd like to apply this to and right click, selecting Place Replicate Apply and the module name.

Eventually, break the module by selecting Groups from the filter in place mode, select the group, right click and then Disband Group.