Abstract: A kind of alkyl phosphinate flame retardant named aluminum β-（N-phenyl carboxamide） ethyl methylphosphinate（Al （CEMP） ）which containing characteristic functional group was synthesizedthrough 2-methyl-2， 5-dioxo-1， 2-oxaphospholane （OP）by two-step reaction of amidation and salification. The structure of the product was characterized by 1 H-NMR、 FTIR and XRD. As the flame retardant being used in PBT，the limit oxygen index （LOI）of PBT with 20wt% Al （CEMP）improves from 16. 6% to 28. 4%，and the vertical burning test reaches UL94 V-0 rating. The test of microcalorimeter confirmed that Al （CEMP）has a strong inhibition effect on heat release rate （HRR）of PBT.

Key words: alkyl phosphinate, flame retardant, P-N synergist, PBT