Brown signed a year ago from the Mackems, but has failed to hold down a regular place in the Canaries first team and dropped further from the reckoning under Glenn Roeder, who brought in Manchester City striker Ched Evans on loan and has been linked with a move for Charlton's former MK Dons man Izale McLeod.
New Preston boss Alan Irvine is said to want to tie up the deal as soon as possible.