Starch is a natural biodegradable polymer material. Poly (butylene succinate) (PBS) is a kind of typical biodegradable polymer material. Environmentally friendly material with high performance price ratio can be prepared by blending starch and PBS. However, the compatibility and mechanical properties of starch/PBS are poor because of starch crystallization. In order to get the starch/PBS blends with excellent performance, magnesium chloride and glycerol were used to modify the starch/PBS blends prepared by melt blending and the infrared absorption characteristics, morphological structure, thermal properties, mechanical properties and crystallinity of the blends were studied. The results show that magnesium chloride and glycerol could produce strong interaction with starch/PBS blends, destroy the original hydrogen bonding and crystal structure of starch/PBS blends, improve the compatibility of starch and PBS, make the glass transition temperature, crystallization temperature, cold crystallization temperature and crystallinity decrease. The mechanical properties of modified starch/PBS blends also change, the elongation at break and tensile strength are improved. When the compounding modifier magnesium chloride content increases, the tensile strength is also increased.