The invention discloses a coconut tree branch and leaf fiber based wood-plastic composite material and a preparation method of the coconut tree branch and leaf fiber based wood-plastic composite material. According to the reparation method, firstly, wasted PE (poly ethylene) bottle covers are prepared into crushed materials with the particle diameter being 40 to 100 meshes, the naturally fallen coconut tree branches and leaves are prepared into fibers with the particle diameter being 50 to 100 meshes, in addition, the recipe comprises the following ingredients in weight proportioning: 55 percent to 75 percent of coconut tree branch and leaf fibers, 15 percent to 25 percent of high-density polyethylene and 10 to 20 percent of other auxiliaries (solubilizing agents, coupling agents, lubricating agents, coloring agents, anti-bacterial agents, ultraviolet ray stabilizing agents, dispersing agents, antioxidants, cross-linking agents and the like), and the coconut tree branch and leaf fiber based wood-plastic composite material is prepared through work procedures such as high mixing, granulation, extrusion, later-period surface processing and the like. The coconut tree branch and leaf fiber based wood-plastic composite material has the advantages that waterproof, mothproof and anticorrosion effects are realized, the woodiness feeling is high, the surface hardness is high, the abrasion resistance is high, the service life is long, formaldehyde is not contained, and the like. The coconut tree branch and leaf fiber based wood-plastic composite material belongs to a typical environment-friendly material for saving materials and replacing wood, can be applied to indoor and outdoor decoration occasions and is particularly suitable for outdoor hydrophilic landscape construction.