Therefore, fully understanding the mechanisms of the effects of resin inside plant fiber lumens exhibits a direct influence on mechanical performance, selection and optimizing the fabrication process of plant fiber reinforced composites. In this work, composites with different amount of resin inside sisal fiber lumens were fabricated. The mechanical properties, such as tensile, flexural and impact properties, and water absorption properties of the composite laminates were studied. Field-emission SEM was used to characterize the fracture surface. The crack propagation mechanisms of the composites were revealed by acoustic emission.