The invention belongs to the field of indoor decoration coating, and relates to an environmentally friendly diatom mud wall material. The material is mainly prepared from, by weight, 50-75 parts of diatomite, 10-13 parts of nanometer titanium dioxide, 10-12 parts of ground calcium carbonate, 5-9 parts of wollastonite powder, 5-8 parts of quartz powder, 4-8 parts of attapulgite powder, 4-8 parts ofsierozem powder, 4-6 parts of graphene, 3-7 parts of propyl gallate, 2-7 parts of negative ion powder, 2-15 parts of a dispersant, 5-9 parts of a surface modifier, 5-10 parts of a mildew-proof antibacterial agent, 2-7 parts of a water resistant agent and 5-8 parts of a binder. The preparation process of the diatom mud wall material is simple, and the diatom mud wall material produced has better mildew-proof and antibacterial properties and excellent strength, flexibility and crack resistance, and overcomes technical problems including easy powder falling, easy cracking, low strength and no stain resistance of diatom mud wall materials.