The invention discloses a method for preparing mulberry silk containing nanometer TiO2. According to the method, firstly, the nanometer TiO2 is prepared into additive solution with the concentration being 100 too 150mg / L, then, the solution is sprayed onto mulberry leaves according to the use dosage that 1.0L of solution is added to 100kg of mulberry leaves, the mulberry leaves are fed to bombyx mori from the fifth instar stage to the 3rd day after being dried until the mounting, in the produced mulberry silk, the content of Ti element is 440+ / -21 to 500+ / -25ng / g, after the silk is washed for 50 times trough water, the content of Ti element is 418+ / -19 to 465+ / -30ng / g, good combination of nanometer TiO2 and silk protein is shown, and water washing resistance and high stability are realized. The method provided by the invention does not adopt chemical agents, the preparation of the mulberry silk containing nanometer TiO2 is realized, and a new research thought is provided for the mulberry silk modification research. The disclosed method has the advantages that the practicability is high, the operation is convenient, the cost is low, the popularization and the application are easy, and the influence cannot be generated on the environment.