Abstract: Expansive soil is multi-cracked and has unfavorable engineering characteristics,which poses a potential threat to projects in expansive soil areas such as slopes. Regenerated rubber reinforced expansive soil(ESR)has good improvement effect on dynamic,static and expansion characteristics of expansive soil. The crack evolution pattern of expansive soil can be affected by the thickness of soil sample. In this paper,rubber-reinforced expansive soil is used to explore the effect of rubber powder on crack evolution of expansive soil and thickness effect of ESR crack. Four groups of samples with different thicknesses without adding rubber expansive soil and ESR are designed for the test. The results are as follows: (1)Water content of expansive soil during natural drying can be divided into three stages. The change of water content of ESR is more rapid. (2)There is obvious thickness effect in the cracking process of expansive soil. But the thickness effect of ESR is less obvious and the crack evolution is more uniform. (3)The total length and total area of cracks during cracking of expansive soils are seriously affected by thickness effect. Rubber reinforcement can restrain the length and area of cracks in expansive soils and reduce the difference between samples of different thicknesses. (4)The fractal dimension of crack development of expansive soil eventually ranges from 1.4 to 1.5. The change of fractal dimension of rubber-reinforced expansive soil with different thicknesses is closer.