Sequential extraction method for soil sulfur was used to determine δ³⁴S values of total sulfur, SO₄^2-, total reduced sulfur (TRS) and organic sulfur in yellow soil, aiming to discuss the transportation and transformation of sulfur and its environmental processes and effects in yellow soil. Organic sulfur was the major sulfur form in yellow soil. SO₄^2- was the major inorganic sulfur form in yellow soil. Total reduced sulfur (TRS) had the lowest δ³⁴S values; meanwhile the parallel increasing δ³⁴S values of TRS and SO₄^2- indicated the occurrence of a bacterial reduction process of sulfate in yellow soil. The δ³⁴S values of total sulfur and organic sulfur firstly increased and then decreased with deepening of soil profiles, which can be explained by mineralization of organic sulfur and the subsequent transportation and adsorption at bottom layers of organic sulfur fractions in yellow soil profiles. The residual SO₄^2- after biological S retention was firstly adsorbed and then desorbed; this desorbed SO₄^2- can transport downward and was subsequently re-adsorbed and accumulated at deep soil layers. This explained the increasing δ³⁴S values of SO₄^2- from surface layers to middle layers and the decreasing δ³⁴S values of SO₄^2- from middle layers to bottom layers in yellow soil profiles. Under acid deposition, the adsorption, desorption and transportation of SO₄^2- can result in soil acidification of yellow soil. It is noted that the deposited SO₄^2- was retained as organic sulfur and adsorbed SO₄^2- in yellow soil, then yellow soil may release more S into rivers by organic sulfur mineralization and desorption of the adsorbed SO₄^2- in a long period after a large decrease in annual sulfur deposition rate. The environmental implications such as changes of soil properties and chemical compositions of river water in southwest China should be investigated in the future.