Abstract: The Mannich reaction of diisopropyl (2-oxopropyl) phosphonate with α-aminosulfone was preliminary studied with tetrabutylammonium bromide (TBAB) as a phase transfer catalyst. The best reaction conditions at 0 ℃, toluene as solvent and 25% sodium hydroxide as alkali were determined through the screening of the reaction conditions. Under the optimal reaction conditions, a series of β-aminophosphonate derivatives were synthesized in 66%−88% yield and the structure of β-aminophosphonate derivatives 5a − 5p were confirmed by ¹H NMR, ¹³C NMR and MS. By the Mannich reaction of diisopropyl (2-oxopropyl) phosphonate with α-aminosulfone, a more effective and convenient method for the preparation of β-amino phosphonate derivatives was developed.