The coaxial electrospinning of two kinds of materials is one of the most popular fabrication methods to endow the composites with desirable properties. For the biodegradable and coaxial-electrospun poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) composite membranes, the effects of spinning parameters and the membrane density on the structure and mechanical property were still uncovered. In this work, biodegradable PLA and PBS composites were fabricated by means of coaxial-electrospinning followed by rolling press. The effects of PLA solution flow rate on the porous and crystal structure of the membrane were initially investigated. It was found that the pore size and porosity were independent on the flow rate. The crystallinity of PLA in the membrane increased with the increasing flow rate while that of PBS decreased, which brought about the composite membrane with enlarged tensile strength and reduced elongation. Then the influence of membrane density adjusted by the roller press was explored. Results showed that the porous structure greatly varied with the density. The larger the density was, the smaller the pore size and porosity were. Meanwhile, when the density was over 322 kg/m(3), the tensile strength and elongation of the coaxial membrane were both higher than that of pure PLA and PBS, achieving the complementary effect of PBS and PLA on mechanical property. The investigation concentrated on the biodegradable PLA and PBS composites is beneficial to the composite materials with complementary properties for various applications.