Fully biodegradable, green composites were fabricated with ramie fibers and modified soy flour (MSF) resin. Defatted soy flour (SF) was modified by a lab-scale filtration system to improve its mechanical, interfacial, and thermal properties through increasing the protein content. The protein content of SF was increased from 53.1 to 67.5% by filtering out soluble sugars using a microfiber-based filter. Tensile stress and Young's modulus of MSF resins were 35.5 and 1411.7 MPa, respectively, which were significantly higher than those (12.7 and 379.3 MPa) of SF resins. Interfacial shear strength of single ramie fibers with MSF resins ranged from 8.8 to 15.2 MPa, which were about 40-50% higher than those obtained with SF resins. Tensile stress and Young's modulus of ramie fiber-reinforced composites were 88.0 MPa and 2.94 GPa with SF resin and 103.8 MPa and 3.15 GPa with MSF resin.