A method of preventing data of a mobile phone from being stolen, particularly the method of preventing personal data stored in a mobile phone from being stolen by the means of sending short messages and inputting an instruction code is disclosed, and the method comprises: defining plurality of confidentiality levels of the mobile phone, and each confidentiality level defines a corresponding instruction code and is added to personal data stored in the mobile phone, and the mobile phone compares and determines whether the short message contains the instruction code when receiving the short message, and reads the confidentiality level corresponding to the instruction code, and updates all personal data of the of the confidentiality level to achieve the effect of preventing the data from being stolen.