<p>Underground rock masses endure multi-dimensional superimposed stresses, resulting in non-uniform stress distribution and exhibiting characteristics of gradient stress. Therefore, understanding the mechanical behavior of rocks under gradient stress conditions is essential for enhancing rock engineering protection and designing effective mitigation strategies. This study proposes a novel experimental method to create a gradient stress environment within the rock and investigate its stress distribution characteristics. Acoustic emission (AE) monitoring techniques were employed to capture real-time acoustic signals and assess the damage evolution in the rock under gradient stress. The internal energy conversion mechanisms were derived through theoretical calculations. By integrating digital image correlation (DIC) technology with failure mode analysis, the deformation and failure characteristics of the rock were revealed. The proposed testing method, validated through theoretical analysis, numerical simulation, and experimental investigation, successfully established a nonlinear gradient stress distribution increasing from the bottom to the top of the specimen. The AE results demonstrated that increasing gradient stress elevated AE activity and increased the proportion of shear cracks. In terms of energy conversion, the gradient stress was positively correlated with rock energy; rapid changes in gradient stress reduced the rate of elastic energy conversion while increasing the rate of dissipation energy conversion. Strain evolution and failure analysis indicated that cracks propagate from high to low gradient stress regions. This research contributes to the understanding of mechanical responses of complex rock structures under gradient stress and provides a basis for future investigations.</p>