A sensing apparatus is applicable to a surgical instrument having a clamping portion, a linkage rod member and an operating portion. The damping portion is used to damp a target. The sensing apparatus includes a touch sensor set, a force sensor, a displacement sensor and a processing device. The touch sensor set can sense a touch signal between the target and the clamping portion. The force sensor can sense a clamping force applied on the target. The displacement sensor can measure a displacement of the linkage rod member. The processing device includes a database, a processing unit and a comparison unit. The database stores reference curves of different reference objects. The processing unit can build an actual measurement curve of the target. The comparison unit can compare the actual measurement curve with each of the reference curves to obtain one of the reference curves corresponding to the actual measurement curve.
