China's parliament is to name Xi Jinping as the country's new president Thursday, formalising his leadership of the world's most populous nation four months after he took charge of the ruling Communist Party.

He will take the reins of the world's second-largest economy alongside incoming premier Li Keqiang, who is due to be anointed on Friday.

Xi's party leadership is his real source of power but the title of head of state will increase his public role, such as on overseas trips, and marks his final step in China's once-in-a-decade power handover.

The government appointment, to be announced after an elaborate but choreographed voting ceremony at a meeting of the National People's Congress, China's rubber-stamp parliament, in Beijing, is effectively guaranteed by his party position.

Since he took its top post in November Xi has pledged to preserve the ruling party's supremacy, as well as vowing to improve livelihoods, implement economic reforms and crack down on corruption, which incenses the public.

Officially he is being elected for a five-year term, but barring extraordinary events or death the 59-year-old will hold the position for a decade.

Xi has already become head of China's top military body, the Central Military Commission, unlike his predecessor Hu Jintao, who at the same stage in the previous transition in 2003 was still substantially overshadowed by Jiang Zemin.

"In recent memory there is no comparable figure who has such power in his hand (so quickly)," said Willy Lam, a politics expert at the Chinese University of Hong Kong.

The presidential appointment makes him an "indisputable supremo", he said. "When Xi travels abroad he will use the title of state president, which entitles him to be on a par with presidents of other countries."

Xi is the son of one of China's most esteemed generals and known as a "princeling", the name given to relations of China's first generation of Communist leaders, who grew up immersed in the ruling party's upper echelons.

But he has threatened to target not only lowly "flies" but also top-ranking "tigers" in corruption crackdowns, warning that graft could "kill the party".

An investigation by US news agency Bloomberg found that Xi's family had amassed hundreds of millions of dollars in assets, casting doubt on his ability to implement major reforms which might threaten their business interests. There was no accusation of wrongdoing on his part.