With a score of 199.4 points in 20 shots, the 25-year-old Zhang handily defeated Vitalina Batsarashkina from Russia, the silver medallist with a score of 197.1.
Anna Korakaki from Greece won the bronze.
Fourth time lucky for Germany's Engleder in 50m rifle
Zhang kept China in top standing in the event after London 2012 and Beijing 2008 gold medallist China's Guo Wenjun failed to qualify for the finals, finishing in 30th place.
Zhang established her lead midway through the event and pulled away with a 10.9 perfect shot in the final rounds. Her score is an Olympic record under the new finals format.
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Anna Korakaki takes gold in shooting for Greece to bag second medal