Abstract: Fracture extension is the cause of collapse failure of silty mudstone slopes. For the fracture extension of silty mudstone, the hydrothermal alternation and Brazilian splitting tests are conducted to analyze the pattern of fracture development. The influences of hydrothermal alternation and fractures on tensile strength are explored, and the fracturing mechanism is studied in combination with the dissipative structure theory. The results reveal that the fracture development in silty mudstone follows a spiral dynamic growth pattern, with a greater degree of development observed during heating than during wetting. The difference coefficient of fracture development gradually decreases from 2.18 to 1.43. The hygrothermal alternation and decreasing fracture inclination degrade the tensile strength of silty mudstone. The energy absorption of the splitting process is weakened with an increasing number of alternations, resulting in a decreasing proportion of elastic energy and an increasing proportion of dissipated energy. The fracture propagation of silty mudstone is a process of gradual formation of dissipative structure. The internal structure is adjusted due to the change of energy and material exchange mode, and the system mutation leads to the formation of fractures. The findings from this study can provide theoretical references for ensuring the safe protection of mudstone slopes.