A new series of dinuclear zinc complexes of the types [LZnEt](2) and [LZn(mu-OBn)](2) ( where L = NNO-tridentate Schiff base ligand) have been prepared. The activities of zinc alkoxides, [LZn(mu-OBn)](2), toward the ring-opening polymerization of L-lactide have been investigated. Experimental results indicate that the reactivity of [LZn(mu-OBn)](2) was dramatically affected by both the electronic and steric effect of the substituents on the Schiff base. The polymerization kinetics using [(LZn)-Zn-1(mu-OBn)](2) ( 2a) as an initiator were also studied, and the experimental results reveal that the rate of reaction is first-order, which depends on both [LA] and [(LZn)-Zn-1(mu-OBn)] (2). Furthermore, the heterotactic PLA with Pr up to 91% can be achieved by initiating of [(LZn)-Zn-5(mu-OBn)](2) in CH2Cl2 at - 55 degrees C.