Three kinds of Schiff base nickel metal complexes: NiL1[N,N’-Bis(2-hydroxy-3-methoxybenzaldehyde)-1,2-ethylenediamine Ni(Ⅱ)], NiL2[N,N’-Bis(3,5-di-tert-butylsalicylidene)-1,2-diaminobenzeneNi(Ⅱ)], NiL3[(1S,2S)-N,N’-Bis(salicylidene)-1,2-diphenylethylenediamine Ni(Ⅱ)] were synthesized and NiL3 was determined by 1H NMR and X-ray diffraction studies. Using NiL1 as catalyst to select the appropriate bulk ring-opening polymerization conditions of L-LA(L-lactide) by single factor analysis, comparison the catalytic polymerization effect of NiL1, NiL2 and NiL3 with different ligands structure features. Structural comparisons revealed that: electron donating methoxy in the catalyst ligand structure was propitious to improve the catalyst activity; steric effect around the metal activity centre of ligand structure was propitious to have polylactide polymers with narrow molecular weight distributions.