Abstract: This study investigates cracking resistance behaviors of ultra-high volume fly ash conventional dam concrete (UHVFACDC) at early age using a temperature-stress testing machine (TSTM), with a comprehensive consideration of temperature history, constraint, deformation and stress of concrete from the prospective of wholism to overcome the deficiency in the traditional methods of thermal cracking property evaluation of concrete at early age. The experimental results show that in comparison with the reference concrete, this fly ash concrete has lower hydration temperature rise, and cracking temperature and its cracking temperature drop is larger. And during hardening, it manifests a smaller coefficient of thermal expansion and a higher degree of tensile creep. All this indicates that UHVFACDC of great early-age cracking resistance is a promising type of green high-performance dam concrete.