Zinc glutarate (ZnGA) is a prominent catalyst for the production of CO2-based poly(propylene carbonate). The original catalysts, ZnO-GA (Cat 1) and ZnAc2-GA (Cat 3), were prepared using ZnO and ZnAc2 as Zn sources, respectively. ZnO-GA-H2O (Cat 2) and ZnAc2-GA-H2O (Cat 4) were prepared by water treatment of Cat 1 and Cat 3, respectively. After water treatment, both Cat 2 and Cat 4 showed enhanced performance for copolymerization of CO2 and propylene oxide. The characterizations demonstrated that H2O is a critical component that not only improves the crystallinity and external surface area of ZnGA, but also increases the number of surface Zn-OH groups. By adding a portion of cyanide, further modification on Cat 4 resulted in a group of ZnAc2-GA-H2O/DMC catalysts (m-Cat 4). The polymerization reached a high yield of 1729 g poly/g Cat and a selectivity of 98.7 % at molar ratio of DMC/ZnGA = 1: 10 (t = 24 h; T = 70 °C; P = 4 MPa). The modified ZnGA/DMC catalyst exhibited remarkable yield and selectivity for the copolymerization of CO2 and propylene oxide to produce high molecular weight alternating copolymers (2.3 × 105 g/mol).