CHENGDU, China — With a neon-red backpack and white Adidas shoes, he looks like any other undergraduate on the campus of Sichuan University in southwestern China.

But Peng Wei, a 21-year-old chemistry major, has a special mission: He is both student and spy.

Mr. Peng is one of a growing number of “student information officers” who keep tabs on their professors’ ideological views. They are there to help root out teachers who show any sign of disloyalty to President Xi Jinping and the ruling Communist Party.

The use of student informers has surged under Mr. Xi, China’s most powerful leader in decades, with hundreds of universities now employing the practice, according to interviews with more than two dozen professors and students, as well as a review of public records.

“Everyone feels they are in danger,” said You Shengdong, a longtime economics professor at Xiamen University in eastern China who was fired last year after students reported him for criticizing one of Mr. Xi’s favorite propaganda slogans.

“How do we make progress,” Mr. You asked, “how can we produce inventions in this environment?”

Universities are posting advertisements recruiting students to spy on their teachers, with some aiming to have one in every classroom. It has created a chilling effect that some have compared to the ideological purification campaigns of the decade-long Cultural Revolution, in which radical students attacked Mao’s perceived enemies.

At a time when Mr. Xi is seeking to ward off supposed threats to social stability and to silence pockets of opposition to his authoritarian policies, students are increasingly playing a key role by monitoring how teachers view Mr. Xi, the party and ideas like democracy. In exchange, they are promised rewards like scholarships, higher grades and advancement within prestigious Communist Party groups.

“It’s our duty to make sure that the learning environment is pure,” Mr. Peng said, “and that professors are following the rules.”

In a throwback to the Mao Zedong era, Chinese universities are deploying students as watchdogs against their teachers, part of a sweeping campaign by Mr. Xi to eliminate dissent and turn universities into party strongholds.

COURTESY NYT