The composite of xanthan gum and clay mixed with sand was used to analyze the crack characteristics of soil surface through a series of dry cracking tests under different xanthan gums and sand contents, and to explore the influence of different xanthan gums and sand contents on the crack resistance performance of soil. In addition, the mechanism of crack resistance is analyzed in depth, and the relevant results have certain reference value for the prevention and control of clay cracks in practical engineering. The results show that both xanthan gum and sand as additives can inhibit the crack development to a certain extent, and the soil under the combined action of them shows better crack resistance. When the content of xanthan gum in clay increases from 0 to 0.25%, the crack intensity factor (CIF) decreases from 11.586% to 0. When the sand ratio is less than 30%, the cracking of soil is less affected. The CIF of the sample without xanthan gum is between 10% and 14%. When the sand rate increases to 70%, the CIF decreases to 1.412%. The composite of sand mixed soil sample containing 0.15% xanthan gum does not crack. Xanthan gum can enhance the cohesion between clay particles and solidify with sand particles to form a stable structure, so as to improve the ability of soil to resist fracture and enhance the crack resistance of clay.