Using molecular dynamics simulations, we investigate the structure and transport properties of solid-liquid interface in a model ordered alloy. Our results show that the studied interface is a smooth interface. Due to the coexistence of structural order and chemical order, the structure of this interface is remarkably different from heterogeneous or pure element solid-liquid interface. The number density oscillates in a complicated way along the interface normal direction, and this oscillation goes into liquid around 30 Å. The two-dimensional structural analysis shows that the atoms form two-dimensional ordered clusters in the transition layer. The diffusion constant gradually increases from zero to a saturation value in the liquid side far from the interface. In the vicinity of the interface, the diffusion constant parallel to the interface direction is large than that along interface normal.