•This review introduces the molding method of multi-dimensional cellulose materials.•The current scenario of the preparation method of cellulose/carbon composites is summarized.•Applications of cellulose/carbon composites in environmental protection are described.•The progress and future potential of composites in water treatment are discussed. Cellulose, as the most abundant natural polymer material on the earth, has attracted worldwide attention due to its characteristics of reproducibility, universality, low cost, biocompatibility and biodegradability. Cellulose-based materials have potential value in supercapacitors, environment and biomedicine. The combination of cellulose and carbon materials can further adjust the microstructure of the composite such as porosity (76–98.8%) and specific surface area (5.07–47.3 m2/g), and enhance the properties of the composite such as the adsorption rate (47–100%) and the degradation rate of pollutants (60–100%), the Young's modulus (1.14–16.6 GPa) and the tensile strength (23.1–277.5 MPa). Besides, composites have the advantages of high electronic transmission efficiency and good reusability, which broaden their applications in water treatment. This review summarizes the molding methods of multi-dimensional cellulose materials, as well as the development status, preparation and modification methods of composites formed by carbon materials such as graphene, carbon nanotubes, activated carbon and nanodiamonds with cellulose, analyzes the research progress and existing problems of the composites in water treatment fields such as adsorption, catalysis, membrane separation and microbial fuel cells, and finally, we make some perspectives for the future researches and applications.