The adoption of bio-based PA56 is expected to replace traditional petroleum-based nylon and achieve carbon reduction of nylon materials. However, the problem of insufficient toughness of PA56 limited its wide applications. Bio-based PA11 was used to toughen PA56 by melt blending, and the compatibility, crystalline behaviour, thermal and mechanical properties of PA56/PA11 were systematically investigated. The results revealed that the blends had only one Tg, indicating that PA56 and PA11 had better compatibility in the blends. The addition of PA11 decreased the crystallinity and crystallization temperature of PA56, but had little effect on its melting temperature. The addition of PA11 effectively enhanced the toughness of the blends, and the elongation at break of the blend increased by 739.8% from 5.27% for pure PA56 to 44.26% with the addition of PA11 at a content of 40%. The impact strength increased by 23.2% from 4.519 MPa of pure PA56 to 5.569 MPa with PA11 content of 20%. The addition of PA11 effectively improved the toughness of PA56, enhanced the comprehensive properties of bio-based nylon materials, and broadened its application field.