That gathering, held every five years, is expected to prompt a reshuffling of several senior party and government positions and lay out the government's policy agenda for the next five years.
But observers say Jin's resignation may also reflect growing concern in the Communist party about the behaviour of senior party members.
His departure comes a day after Hu Jintao, the Chinese president, denounced a lack of integrity among finance officials.
"Comprehensively improve the ideological and political qualities of financial personnel, especially leading officials at all levels," Hu was quoted as telling a meeting of the Politburo on Wednesday, in somewhat cryptic prose.
"Promote a new spirit of integrity, oppose malign trends and noxious influences and create a health professional ethos."
Chinese officials refused to be drawn on speculation over Jin's resignation.
"For personal reasons, Jin Renqing requested to resign," a spokeswoman for China's State Council told the Associated Press news agency.
"The central government agreed to his request and approved appointing him to be deputy director of the Development Research Center of the State Council."
Jin, 63, is one of about 200 members of the Communist party's Central Committee, a former vice-governor of the southwestern province of Yunnan and a former vice-mayor of Beijing.
He had been finance minister since 2003.
Su Ning, the vice-governor of China's Central Bank, said any personnel changes at the finance ministry would not affect the government's monetary policy.