The invention discloses a method and device for automatically converting a sign and a method for automatically reading a sign. The method for automatically converting a sign comprises: disposing a first number of modules dispersedly within the sign, the first number being equal to a number of modules of a two-dimensional code that denote the sign; determining a mapping relation between the first number of modules and the respective modules of the two-dimensional code; and setting the first number of modules respectively to have same properties as the respective modules to which they are mapped of the two-dimensional code, so as to generate a converted sign. With the above method and device for automatically converting a sign, various signs can be automatically converted to machine readable signs, so that people and machines can easily understand these signs.