The invention discloses a preparation method and an application of nano manioc waste. Manioc waste serves as a raw material and is subjected to purification pretreatment and nano treatment; and the nanoscale manioc waste is obtained by a series mechanical method and a chemical method and is applied to reinforcement of high molecular materials such as rubber and plastic. The preparation method of the nano manioc waste is simple in technology and low in cost; a preparation process is green and pollution-free; and the obtained product is good in stability and obvious in reinforcement effect. The technology provides bases for high-valued utilization of the manioc waste and the nano treatment of renewable resources such as polysaccharides, and has a very high popularization value.