The present invention relates to the field of medical instruments. Specifically, a biodegradable cross-linked polymer and a manufacturing method therefor are provided. The cross-linked polymer is obtained by bonding crosslinkable reactive groups to terminal groups of a biodegradable prepolymer having two or more arms and further subjecting the prepolymer to thermal polymerization and/or light irradiation. The cross-linked polymer has an elastic modulus of 10-4,500 MPa, and a degradation rate of 3-36 months. A biodegradable vascular stent and a preparation method therefor are also provided. The vascular stent is formed by laser cutting of polymeric tubing having a three-dimensional cross-linked network structure. The vascular stent has ample mechanical strength, a high elastic modulus at body temperature, and a regulatable degradation rate.