<p>Aiming at the common non-degradable problem of plant fiber reinforced polymer composites and improving the resource utilization of crop waste straw, a degradable composite was prepared by employing PCL as the matrix and rye straw (RP)/oat straw (OP) as fillers in this study. The chemical structure, thermal stability, mechanical properties, water absorption and soil burial degradation behavior of composites were systematically characterized. The results indicated that straw and PCL were bonded to each other through mechanical embedding and no new chemical bonds were formed, and the crystallization of PCL was inhibited by the introduction of straw. Although the thermal stability of composites was reduced with the increase of straw content, the rigidity was significantly improved. The flexural modulus could reach 5 times that of pure PCL when the straw content was 50 wt%, but the toughness and impact strength of the composites were reduced accordingly. The degradation of composites in soil was significantly promoted by the introduction of straw. The mass loss rates of the RP/PCL and OP/PCL composites reached 33.68% and 36.43% in the 60-day soil burial degradation test respectively, which were about 4 times that of pure PCL. Microscopic observation further confirmed that the degradation degree was intensified with the increase of straw content. This study showed that the rigidity of composites was improved and the degradation rate of composites was accelerated by straw fillers, and that it provided effective technical solutions and theoretical basis for the development of green degradable composites.</p>