The invention provides a diatomite micropowder-based interior wall paint capable of removing 
formaldehyde and peculiar smell in 
indoor air and a preparation method thereof, belonging to the field of 
diatom nano-materials. The diatomite micropowder-based interior wall paint provided by the invention overcomes the problems of low purifying efficiency and short-term purifying effect of 
toxic gas like 
formaldehyde in conventional interior wall paints, 
no release of negative ions, poor antibacterial and 
mildew-resistant effects and high cost in the prior art. The diatomite micropowder-based interior wall paint comprises, by weight, 30 to 40 parts of diatomite micropowder, 10 to 20 parts of a nanometer 
titanium dioxide / diatomite composite 
photocatalysis material, 11 to 21 parts of calcined kaolin, 5 to 15 parts of heavy 
calcium carbonate, 2 to 8 parts of light 
calcium carbonate, 0.5 to 2 parts of 
cellulose ether, 1 to 3 parts of lignocellulose, 1 to 5 parts of redispersible latex 
powder and 7 to 17 parts of white 
cement. The interior wall paint has 
formaldehyde and 
toluene purifying efficiency of 86.8 to 88.2% and 52.1 to 54.2%, respectively, formaldehyde and 
toluene purifying effect persistence of 72.8 to 74.0% and 34.8 to 36.0%, respectively, an average negative 
ion increasing amount of 126 to 131 / s.cm2 and an antibacterial rate of 92 to 94%.