The Communist Party of China is convening a congress in Beijing this week that will see a change in its leadership.
Every five years the party congress meets and every 10 years it chooses the top positions.
Chinese President Hu Jintao has opened the congress with a stark warning on corruption.
Addressing more than 2000 delegates, Mr Hu said that a failure to tackle the issue "could prove fatal to the party".
China faced unprecedented opportunities and challenges, he said, and the nation should "aim higher and work harder".
His speech kicks off a week-long meeting that will see a new set of leaders unveiled.
The BBC reports that security is very tight across Beijing, with many dissidents detained or under house arrest, rights groups say.
Mr Hu told delegates at the Great Hall of the People that China had to adapt to a changing domestic and global environment.
"We must aim higher and work harder and continue to pursue development in a scientific way, promote social harmony and improve the people's lives," he said.
China's development should be made more balanced and sustainable, he said, and the "serious challenge" of corruption should be addressed.
The congress - for which no formal schedule has been revealed - will last a week and will be keenly observed for any indications of the leadership's future plans.
During the congress a new central committee is selected. It then chooses the country's highest decision-making body, the Standing Committee of the Politburo.
The process takes place behind closed doors, with the make-up of the top bodies in reality decided ahead of time.
The current Standing Committee has nine members, of whom seven including Mr Hu and Premier Wen Jiabao are expected to step down.
The other two members, Xi Jinping and Li Keqiang, are expected to become party leader and deputy respectively. Mr Xi is also expected to take over from Mr Hu as China's president in March 2013.
Ahead of the congress there has been speculation that the number of seats on the committee will be reduced from nine to seven.