Oligomers of hard and soft segments of unsaturated polyesters were synthesized in two steps. For the hard segment, isophthalic acid was reacted with 1,2-propanediol first, then maleic anhydride was added for further esterification. For the soft segment, diethylene glycol was used to replace 1,2-propanediol. In the previous study, the excess amount of glycol was 20% in weight. In this study, glycol was 10 and 5 wt% in excess, respectively. Decreasing the excess amount of glycol from 20 to 5 wt%, the number average molecular weight of both hard and soft segments increased about 30-40% from 1000 g/mol, and the degree of isomerization of maleic acid changed from 40.5 to 57.3% for the oligomers of the soft segment. The hard and soft segments synthesized in this study were blended in weight ratios from 0 to 100 % in an interval of 20 %, and then cured with styrene for further mechanical testing. The micro-tensile strength of cured soft and hard segments increased 1.3 and 8 times, respectively, in this study compared with that of specimens prepared under the condition of 20 wt% in excess of glycol. Therefore, the criteria of inhibitors can also be achieved by varying the excess amount of glycols. To evaluate the nitroglycerine migration and the erosion rate, only two (60% hard segment and 40% soft segment) of the formulas which passed the criteria of mechanical properties were investigated by replacing lithophone with magnesium hydroxide. In the case of 10 wt% in excess of glycol, the migration of nitroglycerine at infinite time (M