Disclosed is a method for measuring inside dimensions of shoes. In this method a foot model can be obtained after the processes of a plastic filling material being filled into the shoe, shaping, being taken out from the shoe and being restored; then more accurate data of the inside dimensions of the shoe can be obtained by measuring the foot model. Further disclosed is a measuring tool able to be used in the present measuring method. By using the measuring method and the measuring tool, errors encountered when going shopping for shoes can be reduced to the maximum degree by a simple operation, such that the problem that an ordinary consumer could buy a pair of perfect fitting shoes only if he/she tries them personally can be solved.