<p>The failure of rock is a progressive instability process that is always accompanied by the absorption, dissipation, and release of energy. To reveal the failure mechanism of sandstone from the view of energy, a series of true triaxial cyclic loading (TTCL) tests with different intermediate principal stress (<i>σ</i>₂) were carried out using the true triaxial time-dependent testing equipment. The stress-strain curves, strengths, irreversible strains, failure modes, energy evolution and distribution laws of sandstone were analyzed. The results show that as <i>σ</i>₂ increases from 20 to 70&#xa0;MPa, the damage stress, peak strength and residual strength increase by 28.28%, 31.12% and 73.11%, respectively. Mixed tensile-shear failure mode appears on the failed sandstone after the TTCL tests. The maximum total input energy and dissipated energy appear in the specimen failure cycle, while the maximum elastic energy occurs in the cycle before the peak stress. From pre- to post-peak, the energy distribution laws shows obvious segmented features during the whole TTCL tests. When reaching the peak strength, the energy consumption ratio (<i>K</i>) changes abruptly and rapidly increases above 1. Therefore, the sandstone failure can be determined by the abrupt change in <i>K</i> close to the peak strength. These findings provide new insights into understanding the failure mechanism of rock under TTCL, and have significant implications for the stability evaluation of underground rock engineering.</p>