The invention provides a polyvinylchloride (PVC) plastic wood plank and a preparation method thereof. The PVC plastic wood plank consists of the following ingredients: PVC, calcium carbonate, wood flour, azodicarbonamide (AC) foaming agents, stabilizing agents, coupling agents, acrylicester (ACR), paraffin wax, stearic acid and fire retardants. By means of the PVC plastic wood plank, appending proportion of the calcium carbonate is enhanced by reducing the amount of the wood flour, and at the same time, by adjusting the amount of the PVC, and the type and amount of other additives, not only can hardness of the plank be greatly enhanced, but also appropriate toughness can be possessed. Therefore, the plank is guaranteed to be not only possess enough hardness when used as wood floors in public places so that damage and sinking of the surface of the plank are not prone to occurring, but also meet requirements of the wood floors due to the toughness of the plank so that the plank can be ensured to be not easy to crack.