China's government said it expected travellers, bound for home or vacation, would take a total of 2 billion journeys, including plane, train, ship and automobile trips, during the 40 days around the holiday.
To avoid the travel crunch, millions of people, mostly migrant workers, began heading home weeks ago.
Chinese transportation officials estimated that about 4 million people per day would be riding the rails during the month-long travel period.
Huge crowds have descended on
stations and airports
In Taiwan, another mass migration was kicking off on the island of 23 million people.
About 7.5 million Taiwanese, or nearly one-third of the island's population, were traveling home or going on holiday in the next few days.
Kuo Yao-chi, the transport minister, said: "The spring festival is one of the most important festivals of the year, and everyone wants to get home for family reunion as early as possible".
Highways were expected to be so crowded that only cars taking at least three passengers will be allowed.
In Hong Kong, many holiday-makers cheered by a recovering economy have packed up for short getaway trips to the mainland China or abroad.
Officials expect 6.5 billion people, a number close to the total population of the city, to leave or enter the border over the holidays.
Long queues snaked through the city's busy airport on Friday morning, as a record 870 flights were expected to depart or arrive, up 12% from the average daily flight numbers.
Sunday will be the first day of the
Lunar New Year, Year of the Dog
The Lunar New Year is also the only time of year when direct flights are permitted between Taiwan and China.
Regular direct flights were suspended more than five decades ago when the rivals split amid civil war.
Tens of thousands of Taiwanese living in China fly are being allowed to fly home on direct flights.
On Friday, 250 Taiwanese flew to Beijing on a jet decorated with the popular Hello Kitty image.