Abstract: MgO possesses good adsorption properties for heavy metal ions and organic dyes. MgO/Diatomite porous material was synthesized by reasonable calcination once magnesium acetate was loaded in the pores of the modified diatomite. TG-DTA analysis results showed that pure MgO/diatomite porous material was obtained when the minimum temperature for complete decomposition of magnesium acetate was 385 ℃ and its calcination temperature was 400 ℃. Almost all channels of diatomaceous earth were loaded with MgO when the mass ratio of magnesium acetate to diatomite was 3:5. The synthesized porous MgO/diatomite with adsorption performance showed excellent adsorption properties for organic dyes. The saturated adsorption capacity of MgO/diatomite adsorption materials for Congo red was estimated as 2 591.6 mg/g according to Langmuir isotherm adsorption model.