Biodegradable poly(butylene succinate) and a series of poly(butylene succinate-co- hexamethylene succinate) (P(BS-co-HS)) with hexamethylene succinate (HS) comonomer composition ranging from 14 to 35 mol % were prepared in the present work via a two-stage melt polycondensation method. Basic thermal behaviors, crystal structure, isothermal melt crystallization kinetics, and spherultic morphology and growth of P(BS-co-HS) copolyesters with different HS composition were studied in detail with various techniques and compared with those of neat PBS. With respect to neat PBS, the glass transition temperature of P(BS-co-HS) decreases slightly, while the melting point temperature and equilibrium melting point temperature of P(BS-co-HS) are reduced significantly with an increase in the HS composition. Both neat PBS and P(BS-co-HS) have the same crystal structure; however, the crystallinity values are slightly smaller in P(BS-co-HS) than in neat PES. The overall isothermal melt crystallization kinetics of neat PBS and P(BS-co-HS) were studied in a wide crystallization temperature range and analyzed by the Avrami equation. The experimental results indicate that the crystallization mechanism remains unchanged for both neat PBS and P(BS-co-HS); however, the overall crystallization rates of P(BS-co-HS) decrease with increasing HS composition and crystallization temperature. The spherulitic morphology of neat PBS and P(BS-co-HS) were also investigated in a wide crystallization temperature range; moreover, the spherulitic growth rates of P(BS-co-HS) also decrease with increasing HS content and crystallization temperature.