A series of novel biodegradable multi-block copolymers PLGA-(L-Asp-alt-diol)(x)-PLGA with pendant amino groups was synthesized by ring-opening polymerization of D,L-lactide/glycolide(D,L-LA/GA) (75/25) using poly(N-Cbz-L-Asp-alt-diol)s as macroinitiator and stannous octoate as catalyst, in which the N-Cbz-L-Asp represents N-carbobenzyloxy-L-aspartic acid and diols are ethylene glycol, triethylene glycol, PEG200, and PEG600, respectively. Their structures and properties were characterized by FTIR, (1)H NMR, DSC, GPC, and elemental analysis (EA). The contents of the L-Asp unit in the copolymers were increased from 12.9 to 79.3 mmol.g(-1) with decreasing the chain length of the diol, while the glass transition temperatures of the copolymers were decreased from 27.1 to 11.7 degrees C with increasing the chain length of the diol. Thus, the results in this study provide a way to prepare biomaterials with different L-Asp unit densities or different number of bioactive sites as well as different properties through adjusting the chain length of the diol. Synthesis of PLGA-(N-Cbz-L-Asp-alt-diol)(x)-PLGA copolymers.