The invention provides a hydrophobization modification method for ramie nano cellulose. The method comprises the steps of preprocessing ramie nano cellulose and xylan, then carrying out modification reaction on the ramie nano cellulose and xylan, adding the soaked and wetted ramie nano cellulose into a hardwood xylan solution, putting into ultrasonic and dispersing, stirring by a machine, layering the mixture by centrifuging, transferring the upper layer clear liquor, and molding the left concentrated ramie nano cellulose suspension liquid through liquid nitrogen vacuum freeze drying so as to obtain the dehydrated modified ramie nano cellulose. Dehydrated modification is carried out on the ramie nano cellulose by using the acetylation of the hardwood xylan, so that the polarity and hydrophilia of plant fiber are lowered, the agglomeration of nano cellulose is inhibited, and the interfacial compatibility and cohesiveness of the ramie nano cellulose and the hydrophobic resin are improved. The method is simple and efficient, has good repeatability, has environment-friendly processes, uses the environment-friendly modification reagents, and has great scientific significance and considerable application prospect.