Abstract: The concept of lifeworld has completed the sociological turn in Habermas' thought. This turn can be explained from its content and form. In terms of content, although the lifeworld initially appeared in Husserl's late transcendental phenomenology as an important philosophical concept, the interpretation of it contains rich sociological contents. In order to lay the foundation of Weber's theory of meaning in philosophy, Schutz made a sociological transformation of Husserl's concept of lifeworld, which provides meaning for the actions that make up social elements, and action also gives meaning to lifeworld. Habermas reformed the lifeworld from the standpoint of pragmatics, and the lifeworld has become an important concept in his social critical theory. From the perspective of form, Husserl's concept of lifeworld combines the subjective world and the objective world, which negates the modern dichotomy of subject and object, while Schutz further emphasizes the meaning basis and cultural connotation of the objective world or social world from the standpoint of sociology, and his understanding of the lifeworld contains the unity of the subjective world and the objective world. Habermas, on the other hand, starts with the relationship between speech acts and the world, understands the lifeworld as the unity of the objective world, the social world and the subjective world, and reveals the critical power of the lifeworld as the background of communicative action. it has laid a solid foundation for his social critical theory.