A series of tridentate achiral benzoxazolylbased aminophenolate zinc complexes, LZnN(SiMe3)(2) (L = 2-{[benzoxazoly-CH2N(R-3)-]CH2}-6-R-1-4-R-2-C6H2O, R-1 = R-2 = Cl, R-3 = Bn (1); R-1 = R-2 = Bu-t, R-3 = Bn (2); R-1 = trityl, R-2 = Me: R-3 = Bn (3); R-3 = phenethyl (4); R-3 = 3-methylbutyl (7); R-3 = n-hexyl (8); R-3 = cyclopentyl (9); R-3 = cyclooctyl (11); R-3 = 1-adamantyl (12)), was synthesized via the reactions of Zn[N(SiMe3)(2)](2) and 1 equiv of the corresponding aminophenol proligands. All of the complexes were obtained as racemates, and the X-ray diffraction studies confirmed the monomeric structures of typical complexes 11 and 12, where the metal center is tetra-coordinated by three donors of the aminophenolate ligand and one silylamido group. All of the complexes proved to be efficient initiators for the ring-opening polymerization of rac-lactide (rac-LA) at ambient temperature, and the polymerizations were better controlled in the presence of 2-propanol. The substituents on the ortho-position of the phenoxide unit of the ligand and the skeleton nitrogen atom show significant influences on the stereoselectivity of the corresponding complex toward the polymerization of rac-LA, leading to the production of heterotactic biased polylactide (PLA) by complexes 1 and 2 (P-m = 0.40-0.44) and moderately to highly isotactic PLA by complexes 3-12 (P-m = 0.74-0.89). Detailed mechanism studies and microstructure analysis of typical PLA samples revealed that these zinc initiators afforded isotactic stereoblock PLAs via a chain-end control mechanism, and there is no obvious polymer exchange process during the polymerization process.