Inner caliper with staff

The utility model discloses an inside caliper which is provided with a staff gauge and used for measuring the common internal diameter and the metamorphic internal diameter of a workpiece and a tubular product. The inside caliper comprises an inside caliper provided with two measuring arms, wherein a main scale and a cursor are respectively fixed on the two measuring arms, and measuring data can be directly obtained from the main scale and the cursor. The inside caliper can conveniently reach into the various shapes of internal diameters of the workpiece, directly show the internal diameter of the workpiece from the main scale and the cursor which are arranged outside the workpiece to be measured and can conveniently and accurately measure workpiece with various internal diameters. The utility model has the advantages of simple structure, practicality, wide measurement rang, and the like.