At the present moment wet flue gas desulfurization systems (WFGD) are widely used in the SO₂ emitting industries. With the improvement of the SO₂ emission standards and the use of fuel with high sulfur content, there is an urgent need to develop advanced modelling tools to explore the enhancing method of SO₂ absorption process on the condition of flue gas with high SO₂ concentration. In this study, a detailed mathematical model of tray scrubbers, which are adopted in several China’s power plants in order to treat SO₂ rich flue gas, is developed to investigate the influencing factors of the SO₂ absorption process. The model is validated by an experiment using pilot-scale WFGD experimental system and can describe the SO₂ absorption process in WFGD to a satisfactory level. The influence factors of SO₂ absorption of droplets and in spray tower are studied through the model. The effects of pH and tray on desulfurization efficiency are analyzed. Using the tray scrubber is better in order to realize the desulfurization of flue gas with high SO₂ concentration rather than adjusting the pH of the slurry. This model can be regarded as a useful tool for equipment selection and operation optimization of WFGD system.