In backfill mining, the surrounding rock is dynamically damaged by intermittent mining and blasting. After backfilling, bleed water from the backfill seeps into the surrounding rock, leaving the surrounding rock in a water-rock coupling environment. To study the mechanical properties of surrounding rock in such a scenario, two types of granite specimens were prepared, namely, impact-damaged (ID), impact-damaged and water-soaked (IDWS) specimens. A modified split Hopkinson pressure bar (SHPB) system was first applied to execute the dynamic tests with different impact numbers and confining stresses to prepare the ID specimens. Subsequently, the IDWS specimens were prepared by water soaking tests on half numbers of the ID specimens. Finally, static uniaxial compression tests were performed on ID and IDWS specimens. The test results indicate that the peak strength of ID and IDWS specimens increases with the increase of confining stress, and first increases and then decreases with the increase of number of impacts. The total strength weakening factor of the IDWS specimens is composed of the impact strength weakening factor and the water-induced strength weakening factor, as well as the coupling effect of the two factors. Impact loading increases the number of microcracks and pores inside the IDWS specimens, resulting in a larger contact area between water and microcracks and pores. Compared with ID specimens, water induces more tensile cracks in the IDWS specimens according to the results of electron microscope scanning. This is manifested as the transfer from macro shear failure mode to macro tensile failure, and further reduces the peak strength of the IDWS specimens.