Lubricated zinc was introduced into the chemical composition of the main laminate of the Mg-Al hydrotalcite.The chemosynthesis of Mg-Al hydrotalcite,Zn-Al hydrotalcite and Zn-Mg-Al hydrotalcite were investigated and as flame-retardants for flexible poly(vinyl chilride) they were studied by thermal analysis test and LOI test.The results show that,Mg-Al-CO3 LDHs,Zn-Al-CO3 LDHs,Zn-Mg-Al-CO3 LDHs can improve the thermal stability of soft PVC.Under the same conditions,the flame retardant properties of hydrotalcite was better than Al(OH)3 and Mg(OH)2.In the same dosage(20 phr) case,zinc-based ternary Mg-Al Hydrotalcite-like performance was better than the Mg-Al hydrotalcite and Zn-Al hydrotalcite for flame retardancy.