Tea residue activated carbon was prepared using discarded black tea leaf residue and zinc chloride activation. Analytical methods such as infrared spectroscopy and X-ray diffraction were utilized, combined with theories of adsorption kinetics and thermodynamics, to study and discuss the characteristics of Cr(VI) adsorption by black tea residue activated carbon from wastewater, as well as the effects of oscillation time, dosage, pH, and other factors on the adsorption process. The results showed that the optimal conditions for Cr(VI) removal by black tea residue activated carbon are: an oscillation time of 60 min, an activated carbon dosage of 0.4 g, a solution temperature of 40 °C, a solution pH of 2, and an initial Cr(VI) concentration of 50 mg/L.