Based on the rotation of laser displacement sensor, and taking the rotating axis as measuring basis, one novel method for measuring the deep hole straightness is presented and also verified. The experimental results show that, with the precision of laser displacement sensor of ±2 μm, the on-line measurement of the hole straightness can be done with the proposed method. Compared with the relative true value offered by three-coordinate measuring machine, the error is less by 12%. The model just needs the spindle and the feed component of machine tool and can be implemented easily.