Waste peanut shell fiber was used as a kind of reinforcing material in the degradable polymer material poly (butylene succinate) (PBS). The poly (butylene succinate)/peanut shell fiber (PBS/F) composite material was prepared by melt blending method. The crystallization properties, thermal properties and mechanical properties of the composite material were analyzed，and molecular simulations were used to verify the changes in properties. The results showed that the addition of peanut shell fiber did not change the crystal form of PBS, but participated in the crystallization process of PBS as a nucleating agent, which promoted the crystallization of the composite material and shortened the crystallization time of the composite material. When the peanut shell fiber content is 5%, its nucleation effect is the strongest, making it as a "bridge" embedded in the composite material, combined with intermolecular interactions, the thermal and mechanical properties of the composite material are increased compared with pure PBS. The molecular simulation results showed that peanut shell fiber and PBS formed C=O...H-O, to enhance the interface ?between the PBS and peanut shell fiber.