The four employ nearly 70 percent of China's 281.7 million migrant workers, according to data analysis by the 360 Internet Security Center.

The company gathered the results by tracking online ticket bookings for trips made during the 40-day Spring Festival travel rush, which ended on Tuesday. During the period, 2.7 billion trips were made either by train, air, roads or via water transport.

During the annual travel rush, Chinese people return to their hometowns to celebrate the week-long Spring Festival, the most important occasion for family reunions.

Migrant workers heading home for the long holiday and students making trips for winter vacation are the two big sources of population flow.

Qihoo 360's Internet security center, a leading Internet data, search and security service provider, found that South China's Guangdong province, with its strong economy and pleasant weather, is host to 35.2 percent of migrant workers, while Hunan and Hubei provinces in central China were the biggest sources of migrant workers.

The number of Chinese migrant workers topped 281.7 million in 2016, up 1.5 percent year on year.