Langevin is famous for his work on secondary X-rays, the properties of ions in gases, the kinetic theory of gas molecules, the theory of magnetism and the theory of relativity.

Langevin is famous for his research on paramagnetism and diamagnetism. He proposed to use the electron charge in modern atoms to explain these phenomena. He is best known for his research into ultraviolet applications using Pierre Curie's piezoelectric effect. During World War I, in order to detect submarines, he used the piezoelectric vibration of quartz to obtain ultrasonic waves in the water. He began research on using sound waves to detect submarines and determine their position with their echoes. But by the time the device was operational, the war was over. During his research career, he did a lot of work in France to spread the theory of relativity.

In 1905, he proposed the theory of magnetism and used the concept of elementary magnets to give a classic explanation of the paramagnetism and diamagnetism of matter.

In 1908, the fluctuation theory of Brownian motion was developed. At the same time, he resolutely opposed fascism and aggression. During World War II, he was arrested and imprisoned by the German occupying forces and waged a serious struggle against fascism. After the September 18th Incident in China, he carried out various activities to support China and criticized the League of Nations for conniving at the Japanese invaders.