Abstract: The novel complex {[FcCH=CHCO2Sn(nBu)2]2O}2(A) has been synthesized by the reaction of (nBu)2SnO with βFcCH=CHCO2H (Fc=ferrocenyl). This molecule has a center of the structure SnO(Sn2)OSn by elemental analysis, IR and NMR (1H, 13C and 119Sn) spectra. A principle is put firstly forward to assign each carbon peak of the alkyl groups in the type of complex[(RCOOSnR′2)2O]2:(1) to distinguish the endo and exocyclic tin using 119Sn NMR spectrum. The 119Sn signal with larger linewidth should be assigned as an endocyclic tin; (2) to find out which proton of the alkyl chain bonded with endo(or exo)cyclic tin using 1H119Sn HMQC spectrum. The proton of cross peaks through 4J(1H119Sn) coupling which occurs simultaneously to both endo and exocyclic tin should belong to one of the alkyl chain binding directly to endocyclic tin. The proton of cross peak through 4J(1H－119Sn) coupling which occurs only to endo cyclic tin should belong to one of the alkyl chain binding directly to exocyclic tin; (3)to assign each 13C peak of the CH2 groups on alkyl chains through 2D 13C－1H COSY spectrum; (4)to find out which 13C peak of alkyl chains is bonded with endo or exocyclic tin, according to general principle that the 13C peak with higher field should correspond to the proton peak with higher field, that is, if the chemical shift of proton on the alkyl chain bonding directly to endocyclic tin locates at higher field, its related 13C peak located at higher field should belong to endocyclic tin.