Tensile stress is prone to be developed within the dam heel during the operation period of the concrete gravity dam, thereby leading to a weak area. To address the problem of hydraulic fracture in the weak area, experiments are conducted to simulate the hydraulic fracturing process of dam heel under tensile stress, in which a combined loading mode including four-point bending moment and high hydraulic pressure is used. The hydraulic fracturing problem due to initial cracks during construction is explored using different loading combinations. The experimental results show that the variation of the concrete strain is composed of linear and exponential stages during cracking process, and a fracture failure is prone to be developed when the exponential stage is reached. In this case, a small load increment applied will break the steady state with crack failure being extended. It is found that superposed effect is developed due to the splitting water pressure and the tensile stress. When the maximum values of the two stresses are applied at the same place, significant stress concentration at crack tip is developed, which would contribute to hydraulic fracture failure. In contrast, if the two maximum stresses act at different places, the strain distribution on the tensile section of the concrete would be more uniform with its tensile strength being largely mobilized, thereby reducing the hydraulic fracturing effect.