Heavy　metal　pollution　has　caused　worldwide　attention　due　to　its　toxicity　to　people＇s　health.　It＇s　necessary　to　design　and　synthesize　adsorbents　with　excellent　adsorption　performance　in　low　cost.　In　this　work,　diatomite　is　adopted　as　a　self-sacrificing　template　for　the　synthesis　of　adsorbent　Mg-chlorite.　The　three-dimensional　(3D)　hierarchical　porous　Mg-chlorite　perfectly　inherits　structure　characters　from　diatomite　and　exhibits　a　high　specific　surface　area　of　337　m(2)/g.　The　maximum　adsorption　capacities　of　Mg-chlorite　towards　Pb(II)　and　Cd(II)　reach　961　mg/g　and　506　mg/g,　respectively,　higher　than　that　of　the　referenced　adsorbents.　The　Pb(II),　Cd(II)　adsorption　onto　Mg-chlorite　is　a　monolayer　exothermic　process.　Chemisorption　mainly　controls　the　adsorption　rate,　in　which　mass　transfer　exerts　greater　influence　than　intra-particle-diffusion.　Electrostatic　attraction,　chemisorption　and　co-precipitation　are　involved　in　the　adsorption　process,　and　co-precipitation　mainly　contributes　to　the　excellent　adsorption　performance　according　to　XRD,　FT-IR　and　XPS　analysis.　This　study　provides　a　novel　diatomite-template　self-sacrificing　method　in　the　synthesis　of　3D　hierarchical　porous　magnesium　silicate.　The　excellent　adsorption　performance　for　Pb(II)　and　Cd(II)　species　makes　the　low　cost　Mg-chlorite　a　great　potential　in　the　application　of　practical　environment　remediation.