Inst High Energy Phys, Div 1, Beijing 100039, Peoples R China
; Univ Sci & Technol China, Dept Modern Phys, Hefei 230026, Peoples R China
; CCAST, World Lab, Beijing 100080, Peoples R China
Relations between helicity coupling amplitude and L-S coupling amplitude are discussed. The equivalence condition for these two kinematic analysis methods and the Limitations of the L-S coupling amplitude are also studied in this paper.