Mothers in crimson dresses and fathers clutching umbrellas huddled together in drizzly Beijing after sending their children into an exam hall on Friday, the first day of China's biggest "gaokao" tests that will shape the futures of millions of high school kids.

The number of students taking this year's multi-subject gaokao series is set to be a record high, with the Ministry of Education saying that 13.42 million candidates have registered for the high-stakes tests.

"People say that this is the start of a life," 50-year-old mother Zhi Haihong told AFP. "So one cannot slack off."

Zhi donned a traditional qipao dress to take her daughter to the examination site in central Beijing, hoping that its auspicious bright red colour would bring good luck.

China's gaokao drills high school students on subjects including Chinese, English, mathematics, science and humanities, the results of which are critical for gaining admission to university.

High-level education has expanded rapidly in China in recent decades as an economic boom pushed up living standards -- as well as parents' expectations for their children's careers.

The job market that fresh graduates enter is no longer as rosy as it once was as the world's second-largest economy struggles to achieve a post-pandemic recovery, with high youth unemployment a significant concern.

"I think this is a necessary process of growing up," Zhi said when asked about the pressures young people face.

"(The gaokao) is also a method for the country to select talented people," she said.

"Only after undergoing pressure can one's mental tolerance increase. Then you will be able to withstand these pressures in the future when working in society.

"I think this is understandable."

- Praise from space -

A list of top-trending topics on social media site Weibo on Friday morning was studded with exam-related discussions, with many users sharing pictures of uniformed students exchanging high-fives and hugging their parents before entering testing centres.

Even the official Weibo account of China's Chang'e-6 lunar probe, which began carrying samples back to Earth from the far side of the Moon on Tuesday, offered encouragement.

"Every one of you that is striving hard is terrific," it said.

Images from across the country taken Friday morning showed students and well-wishers preparing for the first session.

In the central city of Wuhan, crowds of parents stood behind a barrier as test takers clutched documents on their way into the examination centre.

Education authorities are on high alert each year after elaborate cheating attempts were uncovered in previous years.

Areas around testing centres are often tightly controlled, with traffic diverted and honking prohibited to ensure a comfortable environment so that test takers can concentrate.

Sun Song, a 45-year-old father, stood under an umbrella in Beijing chatting with other parents after seeing his daughter off before her first exam.

"It will be enough if she can find a job she likes and get into a school she likes," Sun told AFP.

"As long as the kid is happy, it's enough."

- 28th time lucky? -

After failing for the 27th time to get into his dream university through the gaokao last year, 57-year-old millionaire Liang Shi is giving it another go.

Liang worked his way up from a menial factory job to establish his own construction materials business but said he has yet to become "an intellectual" worthy of Sichuan University.

The plight of the "gaokao holdout" has been closely watched by the media and online in recent years.

However, Liang said it could be his last attempt if he doesn't make the grade this year.

In another closely watched case, 35-year-old Xu Mengnan is taking the gaokao again 16 years after he deliberately flunked the exams in protest against the education system.

Xu has worked in factories in eastern China, married, had children and divorced since that act of defiance but decided to hit the books again in 2017 for another try.

He passed in 2018 and graduated last year from an art college in eastern Anhui Province, but this year he wants to get into university to take his studies further.

Pursuing an education major would allow him to "fulfil (his) dream", the Henan Business Daily reported.