Most research on biomass-filled plastic composites (BFPCs) mainly focuses on their formulation and physical/mechanical properties, but studies on the connection performance of BFPCs are very rare. However, such performance is vital in the quality assessment of BFPCs products and plays an important role in improving product quality and promoting its application in the field of architecture and furniture. Therefore, the behavior of L-type BFPCs structure under the interaction of fatigue-creep was investigated. Results suggested that the fatigue-creep curve is a typically three-region curve at 80% and 60% failure load, and only first two stages at 40% failure load. But the damage caused by fatigue-creep interaction was not a simple superposition. Fatigue damage dominated when the holding time was short, and creep damage occupied a dominant position gradually when the holding time was longer. In addition, the lifespan of the BFPC component increased initially and then decreased as holding time increased. The component joint exhibited the least integrated damage when the holding time was 60 s and the lifespan was longer.