The Ministry of Supervision and Central Disciplinary Committee said Mr Sun had “seriously violated party discipline” and was removed from all positions and kicked out of the party. He allegedly siphoned off a large but undisclosed amount of public funds during his time in office and squandered it on a “decadent lifestyle”.
In fact he is suspected of taking 40 million yuan (just under US$ 6 million), originally earmarked for a flood control project in Guilin, by falsifying documents.
Local papers have accused him of extramarital affairs with four married women.
The investigation into his activities began last year when a husband of one his mistresses reported his activities to the government.
Mr Sun became Guigang's mayor in the 1990s and was promoted to the post of Guangxi deputy chairman in 1998 at the age of 41. As a young official from an ethnic minority, he was once widely expected to be in the running to become the region's chairman.
Before he was expelled, he was responsible for agriculture, water conservation, forestry and civil affairs.
Mr Sun's expulsion comes two days after the removal of Yu Youjun as party secretary of the Ministry of Culture after he was implicated in two corruption cases in 2002 and 2003 when he was mayor of Shenzhen. Hitherto he had been a rising star in the Communist Party.
Despite face-saving statements by central authorities the fact remains that corruption is high among party officials and provincial administrators who ride roughshod over the rights of ordinary people, confident of the impunity that comes with their office and the difficulties anyone has in complaining.