The invention provides a preparation method of a superhydrophobic fabric or superhydrophobic non-woven fabric, which comprises the following step of: enabling a fabric containing C-H bonds or a non-woven fabric containing C-H bonds to be subjected to irradiation grafting reaction with a monomer containing long-chain alkane, thus obtaining the superhydrophobic fabric or superhydrophobic non-woven fabric, wherein the monomer containing long-chain alkane is a compound as shown in general formula (1), X is hydrogen or methyl, and n is 10-17, preferably 13-17. The invention overcomes the defects that the existing preparation process of the superhydrophobic fabric or non-woven fabric is complicated, the duration time of the modification effect is short, and the superhydrophobic fabric or non-woven fabric is intolerant of washing, is of certain toxicity, is high in cost and the like, thereby providing a washing-resistant permanent superhydrophobic fabric or non-woven fabric and a preparationmethod thereof. Since the used monomer is a non-fluorine monomer having the advantages of low toxicity, low cost and the like, the invention is beneficial to large-scale industrial production. The general formula (1) is shown in the specification.