A study of the modified diatomite prepared by the PAM coated on the surface of the raw diatomite and applied to treat the simulated wastewater with intensive concentration of lead ions [Pb(Ⅱ)]. Pb(Ⅱ) has been considered as one of some significantly toxic heavymetals (Cd,Cr,Pb, Mn,Cu,Zn,et al) contaminated the surfacewaters. The results indicated that modification could enhance the diatomite and acidic heavymetal wastewater’s compatibility; Obtained that modified diatomite’s saturated adsorption capacity could reach 66.15~ 68.95mg/g, superior to raw one; At the same time, the comparation of four common adsorbents and modified diatomite’s adsorption capacity under some given conditions showed: modified diatomite > zeolite > vermiculite > raw diatomite > red soil; Observed by SEM, PAM molecule arrayed on the diatomite’s surface smoothly that improved its interior structure and the charge on the surface, even enhanced the sedimentation performance of the diatomite in heavymetal wastewater.