The director of the Beijing Liaison Office in Hong Kong, Jiang Enzhu, is to be replaced by his deputy, Gao Siren, according to Xinhua.
It will be the first time since 1989 that Beijing has not appointed a career diplomat to the post. Mr Gao, 58, was deputy secretary of the Guangdong provincial committee of the Chinese Communist Party before he took up the Liaison Office deputy-director post four years ago.
A deputy of the National People's Congress (NPC) said the appointment could help strengthen co-operation between the SAR and the Pearl River Delta region. Mr Jiang, 63, a former ambassador to Britain, has held the post since he replaced Zhou Nan in 1997.
The official news agency's report did not say when Mr Gao would assume the job or when Mr Jiang would leave Hong Kong.
But according to sources, Mr Jiang will return to Beijing this week to attend an NPC standing committee meeting. Mr Jiang is expected to head a panel under the standing committee.
As director of the Liaison Office, Mr Jiang, a former deputy foreign minister, adopted a low profile to avoid being seen as meddling in Hong Kong's affairs.