State news agency Xinhua said the rocket, carrying the ChinaSat-4B satellite, exploded after an in-flight anomaly following lift-off at the Wenchang space launch site.
The mission was unsuccessful, and the cause of the explosion is being investigated, the agency added.
It was the Long March 7A's first failure since March 2020, when it experienced an in-flight malfunction.
The rocket later completed more than a dozen successful flights before Monday's mission, according to Chinese launch records.
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