Collapsible ruler

The utility model discloses a collapsible ruler, which is formed by the combination of two rulers glidingly assembled into integration; the two rulers face each other and are parallel mutually. When measuring, firstly, the two rulers are pushed and shrank to be together; the step of the box body is passed round, and then the outer end of one of the two rulers is held on one surface of the measured object, however, the other ruler is pulled outwards until the outer end of the ruler gets to the other surface of the object to be measured; at this time, the distance between the two measured surfaces can be read. The collapsible ruler designed by the utility model can measure the distance between the flat surfaces; the outer ends of the two rulers are processed into arc shapes, and also can be used for measuring the distance between the curved surfaces. The collapsible ruler of the utility model overcomes the difficulty of measuring the internal dimension of the object having the steps in the past, and has the practicability and the generalized and applied values.