A deep knowledge of the failure mechanisms and early warning of dangerous rocks is an important issue in geological disaster prevention and reduction. This study focuses on the failure analysis of dangerous rocks from a laboratory scale, whose models are prepared by 3D printing (3DP) technology. The frozen–thawing test (FTT) is performed to reproduce the failure processes of toppling and falling types dangerous rocks. In addition, the digital image correlation (DIC) technique is applied to detect the deformation characteristics of dangerous rock models during the tests. The relative displacements along the structural plane and the displacement vectors on the dangerous rock surface are further extracted to quantitatively reveal the failure mechanism from a fine-view perspective. It is found that the toppling type dangerous rock is dominated by the rotational failure, while the falling type dangerous rock is dominated by tensile‒shear failure. Furthermore, a DIC-based early warning method is proposed for identifying the precursors of dangerous rock instability from a laboratory perspective. The results provide an important application and reference value for the study of dangerous rock prevention and reduction.