The invention relates to a composite material, and particularly relates to a waste tire rubber powder-filled plastic wood profile and a preparation method thereof. The waste tire rubber powder-filled plastic wood profile of the invention is prepared by the following raw materials by mass: 15%-75% of plastics, 10%-70% of wood fibers, 5%-40% of waste tire rubber powder, 5%-45% of a fire retardant, 1%-10% of a compatibilizer, 0.1%-3% of a lubricant, 0.5%-3% of a plasticizer, 0.05%-4% of an anti-oxidant, and 0.05%-2% of a vulcanizing agent. According to the invention, the plastic wood profile is filled with the waste tire rubber powder, which not only improves the resource utilization rate of waste tire rubber powder, develops new application technology of the rubber powder, extends the application scope of the rubber powder, but also provides good mechanical properties for the prepared plastic wood profile, greatly reduces the production cost of the plastic wood profile, and is expected to further extend the application fields of the plastic wood profile.