The properties of ethylene succinate copolymers containing aliphatic diols and dicarboxylic acids in an amount of 5 and 10 mol % as a third comonomer are studied. These copolymers are semicrystalline polymers, since their crystallinity is 1.5–2.0 times lower than that of poly(ethylene succinate). It decreases linearly with an increase in the weight content of the third comonomer. At the same time, the crystallinity of the polymers containing moieties of sebacic and decanedioic acids is significantly higher than that of other polymers. The elastic modulus of the polymers almost linearly depends on the weight content of the third comonomer. The introduction of diols in the composition of the polymers contributes to their strain hardening. The glass transition temperature of the polymers decreases with increasing length of the carbon skeleton of the comonomers. The rate of degradation of the copolymers in wet soil increases by 1.5–2.0 times relative to the rate of degradation of poly(ethylene succinate).