A water-rich high-geostress strike-slip fault simulating test chamber includes a first chamber and a second chamber. A flexible chamber is fixedly connected between the first chamber and the second chamber; the flexible chamber includes a plurality of flexible fault connecting units; each of the flexible fault connecting units includes framework flanges, a rubber ring, and a steel plate nested in the rubber ring; the framework flanges are respectively fixed at two axial sides of the rubber ring; and two adjacent flexible fault connecting units are connected through a bolt device fixed on two adjacent framework flanges. According to the present disclosure, the flexible chamber includes a plurality of flexible fault connecting units. The framework flanges are configured to connect the plurality of flexible fault connecting units. The rubber ring is able to realize axial tensile deformation and horizontal shear deformation, as well as a sealing function under pressure.