<p>The weathered red-layer mudstone (WRM) is prone to disintegration engineering problems caused by humidity changes. Under desiccation conditions, WRM experiences cracking due to decreasing water content. Considering the similarities between desiccation cracking of WRM and clay, it is important to study the cracking characteristics of WRM for further research on the disintegration mechanism of WRM. This study conducted desiccation tests on WRM under different environmental temperatures and layer thicknesses. The geometric structure and morphological features of the crack network during the cracking process with varying water content was quantified. Experimental results indicate that as the water content decreases, the total crack length (<i>L</i>), average crack width (<i>W</i>_m) and surface crack ratio (<i>V</i>_s) of WRM initially increase rapidly and then reach a stable state. Smaller layer thickness result in the lower <i>W</i>_m, <i>V</i>_s, initial cracking water content (<i>w</i>_I) and residual water content (<i>w</i>_R), but the larger <i>L</i>, number of cracks and crack nodes. Higher temperatures result in the lower <i>w</i>_I, <i>w</i>_R,<i> L</i>,<i> V</i>_s and number of cracks as well as crack nodes, but the lager <i>W</i>_m. Micro X-ray computed tomography test results reveal that desiccation cracks of WRM first vertically and then gradually deviate and develop obliquely towards the bottom as the water content decreases, which can be explained by the principles of I–II compound fracture mechanics. Experimental research on desiccation cracks provides a new perspective for understanding the disintegration mechanism of WRM.</p>