BEIJING — When he was 14, Li Yangyang’s prospects were grim. A middle school graduate who moved to Beijing with his parents from the countryside in 2009, he worked long hours in a restaurant for less than 700 renminbi a month.

Then a fellow rural migrant, who had also moved to Beijing, introduced him to BN Vocational School, China’s first tuition-free, nonprofit vocational secondary school.

Now 17, Mr. Li is studying hotel management and hoping to enter an industry in which the starting salary is more than triple his old wage of about $100 a month. “I feel lucky to be at B.N.V.S.,” he said, as he prepared to apply for internships at the capital’s luxury hotels. “My future is much brighter, and I have more opportunities because of it.”

For those like Mr. Li, the children of China’s 200 million migrant laborers, vocational schools offer the promise of better-paying, more stable work than their parents had.