Foamed HDPE/bamboo powder composites were prepared by two step molding foaming method with HDPE as plastic matrix, Azodicarbonamide (AC) and zinc oxide (ZnO) compound as foaming agent and oxidation of Dicumyl Peroxide (DCP) as cross-linking agent. The effects of cross-linking agent on the density, rebound resilience, foaming property and mechanical property of the composites were studied. The results indicated that with the cross-linking agent content being 0.6wt%, the density of foamed HDPE/bamboo powder composites reached the minimum value of 0.054 g/cm3, and the rebound resilience ratio reached the maximum value of 90.5%. With the cross-linking agent content being 0.4wt%, the pore distribution of the foamed composite was relatively more intensive and uniform, and the bending strength reached the maximum value of 29.3 MPa, about 8.2% lower than that of non foamed composite, while the impact strength was 6.8 kJ/m2, about 16% lower than that of non foamed composite.