The Spanish side are one of six teams Arsene Wenger's group runners-up could face, alongside Paris St Germain, Malaga, Borussia Dortmund, Juventus and Bayern Munich.
Song swapped Emirates Stadium for Camp Nou when he joined the Arsenal exodus during the summer and expects only one outcome if they meet for a place in the quarter-finals.
"Of course I would like to play against Arsenal. For me to go back there, where I had seven magnificent years, would be something very special," said the 25-year-old.
"If we draw Arsenal I'd be happy to see the fans again and go back to the club, even though if we go there it will be to get the best result possible.
"Arsenal's a big club, but Barcelona's a level above because of the talent of the players there.
"That's no disrespect to Arsenal because they have talented players, but I think the Barcelona players are above them. I saw a lot of people come and a lot of people go at Arsenal."
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