Abstract: Thermal stress induced by cement hydration is a critical factor causing cracking in mass concrete foundation slabs. Appropriate curing methods can effectively mitigate such cracking. To investigate the impact of geotextiles with different thicknesses on the curing effect of mass concrete in foundation slabs, this study incorporates real-world engineering data and calculates essential parameters including the adiabatic temperature rise of concrete hydration heat, the heat transfer coefficient of curing material, and the standard value of concrete tensile strength. A hydration heat analysis model for typical areas of the foundation slab was established using Midas/FEA finite element analysis software, and detailed simulation analyses were conducted on the curing effect of concrete covered with geotextiles of varying thicknesses. The results show that when the surface of the mass concrete in the foundation slab is covered with 6 mm thick geotextile for curing, the surface tensile stress exceeds its standard tensile strength from day 0 to day 5, and there is still a risk of cracking at early ages. In contrast, when the geotextile thickness is increased to 40 mm, the surface tensile stress of mass concrete at all stages is lower than the standard tensile strength, significantly reducing the cracking risk after concrete placement.