Wen confessed this during an inner-party discussion group in January, Hong Kong-based South China Morning Post reported.
"Failing to persuade my children not to do business [in China] is a significant mistake of mine," Wen reportedly said.
"It's my biggest regret in life," the Post quoted local reports as saying.
Last year Wen and his family refuted allegations to an investigative report by the New York Times detaining assets accumulated by his family through diamonds and insurance businesses and threatened to take legal action which has not materialised so far.
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Wen's wife Zhang Peili like him is a geologist who had diamond business. His two sons reported to have their business.
According to the Post Wen also admitted that other areas of his premiership were unsatisfactory, including dealing with petitioners and immigrant workers and curbing corruption inside China's medical system, the report said.
Wen, 70 is known for his humble roots in China.
But his image was suffered a serious setback after a New York Times report.