When blasting excavation of deep high water pressure rock project, the surrounding rock body is subjected to the combined effect of high water pressure, high ground stress and blasting dynamic load. Due to the lack of kinetic test methods and test systems for rocks with high hydraulic pressure and high ground stress, its theoretical research lags far behind engineering practice. In this paper, based on the self-researched test system, stress wave propagation tests are conducted on red sandstone to explore the attenuation law of stress wave propagation in red sandstone under the combined action of high water pressure and high ground stress. The results show that when the impact velocity and axial static stress are certain, the stress wave velocity of red sandstone gradually increases with the increase of water pressure, and the wave velocity changes as a quadratic function with the increase of water pressure. In the fitting function, the quadratic term coefficient, the primary term coefficient and the axial static stress show a linear correlation, and the constant term and the axial static stress show a nonlinear correlation. For the red sandstone with small initial damage, the presence of water pressure causes the fractures inside the rock to be squeezed, which enhances the rock wave impedance and facilitates the propagation of stress waves in the rock specimen.