Abstract: Marx and Engels investigated the living conditions of young people in Western European capitalist society in the 18th century, explained the historical status and important mission of proletarian youth, advocated the all-round development of young people, established the ideal of striving for the liberation of all mankind, criticized the capitalist system and bourgeois education, and formed the Marx and Engels’ concept of youth. We can understand and grasp the core essence of Marx and Engels’ concept of youth from the aspects of main content, distinctive features, and practical requirements. From the perspective of the enlightenment of the times, General Secretary Xi Jinping’s important thinking on youth work inherits and develops the core essence of Marx and Engels’ youth concept, reaffirms and promotes the value of the times of Marx and Engels’ youth concept, and is the fundamental compliance of the party’s youth work in the new era.