Label-free microscopic imaging technology includes the optical coherence tomography, photoacoustic imaging, nonlinear imaging, and microsphere lens imaging technology. The commonly used label-free imaging techniques are introduced, and the traditional and advanced imaging principles are summarized. The advantages and disadvantages of such various of label-free imaging technologies and the latest research progress are introduced in detail, including the applications of such imaging technology in various fields. Finally, the future development of multi-modal imaging technology based on unmarked microscopy technology is prospected.