Sandy bank slopes are widely distributed near rivers and lakes, and desiccation cracking is ubiquitous on the slopes' surface. It negatively impacts the mechanical and hydraulic properties of the topsoil. Sand grains have a profound effect on the structure and physical properties of the sand-soil mixture. This study investigated the effect of incorporating sand on the desiccation cracking and moisture dynamics of mixed soil at temperatures of 35, 50, and 65 degrees Celsius and to reveal the mechanism of sand grains influencing the desiccation cracking. The sand contents selected are 0%, 10%, 20%, 30%, 40%, 50%, 60%, and 70%. The results indicated that the mixed soil at low temperatures maintained a high moisture content, resulting in a slow evaporation rate. At low temperatures, the number of crack segments increased, and the block area decreased. The incorporation of sand could improve the porosity and increase the proportion of macropores, inhibiting crack formation. Adding sand could lengthen the overall drying period by prolonging the upward pathways and reducing the cross-sectional area of water migration. This study can help in analyses of crack formation of sandy slopes' topsoil.