The invention relates to a preparation method of a cellulose based nano composite fabric containing silsesquioxane particles and aims to provide a preparation method of a cellulose based nano composite fabric containing silsesquioxane particles so as to obtain a finished fabric with favorable elasticity, anti-wrinkle property and high color fastness. The preparation method in the technical schemefor solving the problem comprises the following steps of: firstly, preparing a POSS-H methanol solution with a certain concentration; then mixing the solution with magnesium oxide and citric acid in a certain proportion to prepare a finishing liquor; and finally paddling a pure cotton fabric into the finishing liquor by utilizing a padder to obtain the nano composite fabric in the invention. The invention can be used in the fields of functional materials, spinning, and biological materials.