Complex sentence: Notified by U.S. authorities that he was free to go, Qian immediately arranged his departure, leaving for China in September 1955, on the passenger liner "SS President Cleveland" of American President Lines, via Hong Kong.
Split into simpler sentences: Notified by U.S. authorities that he was free to go, Qian immediately arranged his departure. He left the United States in September 1955 on the passenger liner "SS President Cleveland" of American President Lines, arriving in China via Hong Kong.