Using　the　porous　framework　of　CaO　as　templates　and　reagents,　we　explored　a　surfactant-free　and　economical　method　for　preparing　calcium　silicate　hydrate　(CSH)　hierarchically　ordered　nanostructures.　Incorporation　of　SiO2　nanoparticles　into　the　CaO　framework,　followed　by　a　reaction　assisted　by　hydrothermal　treatment,　resulted　in　the　formation　of　CSH　with　well-defined　morphologies.　The　structural　features　of　CSH　were　characterized　by　3-D　hierarchical　networks,　wherein　nanofibers　assembled　to　form　nanosheets,　and　nanosheets　assembled　to　form　hierarchically　ordered　structures.　Investigation　of　the　crystal　growth　mechanism　indicated　that　the　key　to　forming　the　CSH　ordered　assembly　structure　was　confining　the　Ca/Si　ratio　within　a　small　range.　Nonclassic　oriented　aggregation　mechanism　was　used　to　describe　the　crystal　growth　of　nanosheets,　while　the　porous　CaO　framework　served　as　template/reagents　responsible　for　the　formation　of　hierarchical　structures.　The　resulting　CSH　adsorbent　exhibited　better　performance　in　removing　Pb(II)　compared　with　other　types　of　random　CSH　adsorbents.　Additionally,　the　hierarchical　structure　of　CSH　provided　more　pores　and　active　sites　as　support　for　other　active　functional　materials　such　as　zerovalent　iron　(Fe0).　As-produced　CSH@Fe　nanocomposite　with　self-supported　structures　displayed　high　capacities　for　removal　of　Pb(II)　after　five　adsorption-desorption　cycles,　and　high　capacities　for　other　heavy　metal　ions　(Cu2+,　Cd2+,　and　Cr2O72-)　and　organic　contaminants.　©　2016　American　Chemical　Society.