Abstract: Effectively strengthening the surface sulfidation is essential for recovering hemimorphite by froth flotation. In this work, inductively coupled plasma optical emission spectrometer (ICP-OES) measurements, Visual MINTEQ calculation, X-ray photoelectron spectroscopy (XPS) analysis, time of flight secondary ion mass spectrometry (ToF-SIMS) analysis, and micro-flotation experiments were explored to systematically investigate the effect of ammonium sulfate ((NH₄)₂SO₄) on the formation of zinc sulfide species on hemimorphite surface and its role in sulfidation flotation. The results showed that (NH₄)₂SO₄ exhibited a positive influence on hemimorphite sulfidation flotation. It was ascribed to the number of zinc components in the form of Zn²⁺ and Zn(NH₃)_i²⁺ (i = 1–4) increased in the flotation system after hemimorphite treatment with (NH₄)₂SO₄, which was beneficial to its interaction with sulfur species in solution, resulting in a dense and stable zinc sulfide layer generated on the hemimorphite surface. Zn(NH₃)_i²⁺ participated in the sulfidation reaction of hemimorphite as a transition state. In addition, the sulfidation reaction of hemimorphite was accelerated by (NH₄)₂SO₄. Thus, (NH₄)₂SO₄ presents a vital role in promoting the sulfidation of hemimorphite.