Abstract: Friedel′s salt belongs to a kind of mineral-hydrocalumite（aluminum-calcium layered double hydroxide LDHs）.It can through three different mechanisms，namely the surface adsorption，interlayer anion exchange，and the reconstruction of the memory effect（cation exchange of layer board），to remove various heavy metals cationic and anionic pollutants from water. A oxide-salt precipitation synthesis method was developed with lime milk and liquid calcium containing polymerization alu- minum（PACCa） as raw materials，in which complex ion of ［Ca2Al（OH）6]+ as Friedel′s salt nucleation center，in alkaline conditions directly interaction with the Ca2+，Al3+，and Cl- in the solution，to take part in Friedel′s salt crystal growth.The procedure saved the nucleation reaction，thus had lower energy consumption and an accelerated reaction rate.On this basis，the experiment of Friedel′s salt as flocculation-adsorbent of heavy metals on the electroplating waste water deep purification was carried out.

Key words: Friedel&prime, s salt；oxide-salt precipitation synthesis；electroplating wastewater；dissolving-recrystallization；removal of heavy metals