In reply to Chandra Bhushan Singh:
I guess I don't understand your question well enough to answer it.
If you want to use UVM to create a component that will model system memory outside of (but presumably connected to) your DUT, you can. This would be what we call a slave agent in the Cookbook, where you have a testbench component that connects either to your DUT or to something else in your testbench. Does that help?