He is reported as having died on Sunday while in Europe for trade and business talks.
His passing has sparked an outpouring of shock and admiration from both sides of the House.
"Very sad to learn of Simon Crean's passing. We were good friends through thick and thin. A loyal servant of the Labor Party," former trade minister Craig Emerson wrote on Twitter.
Erstwhile defence minister Joel Fitzgibbon tweeted: "I'm shocked by the news of Simon Crean's death. Far too young. A good and talented guy, history will treat him kindly."
Opposition Leader Peter Dutton called him "a gentleman".
"I always admired Simon for his intellect and decency... A very sad day,"Â he tweeted.
Former prime minister Tony Abbott wrote of "a thoroughly admirable man".
"He never made the mistake of identifying the well-being of the country with his own personal advancement," he said in a statement.
Labor's Tanya Plibersek remembered him as: "Smart, principled, courageous and kind. He will be missed."
Once the president of the Australian Council of Trade Unions, Mr Crean then became an MP for Hotham, Victoria, serving first under prime ministers Bob Hawke and Paul Keating.
He served as federal Labor leader from 2001 to 2003, across the floor from John Howard, and when Kevin Rudd secured a Labor victory in 2007, he was given the trade portfolio in cabinet.
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