Abstract: The fatigue properties of two types of wood (P. Ussurensis and B. Platyphylla) and wood plastic composites were analyzed by three-point bend fracture testing, and fatigue crack propagation models were investigated. Test results show that the maximum stress of wood plastic composites presents a linear relationship with logarithmic fatigue life. Fatigue load increases linearly with enhanced polymer content. For P. Ussurensis, the slope of S-N fatigue curve is influenced by polymer content in wood, and fatigue crack grows along wood fibre. For B. Platyphylla plastic composites (PC>30 wt.%), fatigue crack grows in the shape of 'Z’ along the height of the specimen.