The work aims to introduce the biomass fiber materials such as reed, pulp and jute into Poly(Butylene Adipate-co-Terephthalate) (PBAT) to prepare high-performance rigid biodegradable composites by a high-speed blender. The effects of different biomass fibers and their content on the structure, properties and biodegradability of the composites were investigated. The bending modulus and strength of the PBAT/biomass fibers composite were significantly improved. Among the three composites, the PBAT/pulp composite showed the best mechanical properties and thermal stability. For the PBAT-doped pulp with a 60% mass fraction, the bending modulus and bending strength reached (1055±35)MPa and (12.46±1.1)MPa. The degradation test showed that the degradation rate of the composite was significantly higher than that of PBAT, which was related to the water absorption and size of the biomass fibers. The rigid biodegradable composites obtained by filling PBAT with large size biomass fibers have excellent comprehensive performance, which provides scientific ideas and technical basis for the development of green biodegradable rigid packaging and packaging filler materials.