Redknapp, writing in his column in The Sun newspaper, said: "The Champions League is fast replacing the Carling Cup as a stage for the reserves to enjoy a few days in a pretty, foreign town and a run out."
Redknapp, whose Portsmouth side are currently fifth in the Barclays Premier League, a position at the end of the season that would guarantee a place in the UEFA Cup, admitted his views might "sound odd".
"It is because of the huge disparity between the teams and, moreover, what I regard as the monotonous, plodding group stages," he said, adding that it only gets interesting in the second round.
Redknapp points out the games that are interesting are those that take on "the feel of the traditional, old knockout match".
He said: "I am speaking not as a manager and member of the football fraternity but as a punter who likes to watch exciting games on TV."
Redknapp also said the UEFA Cup was suffering the "same syndrome", but admitted: "I know the big clubs' chief execs would be dead set against reverting to the old format."