The effects of soluble ions on the morphology and crystal growth of calcium sulfate hemihydrate whiskers are very significant. In order to gain a deeper understanding of the basic theory of regulating whiskers, this paper summarises the progress of research on the effects of different types and concentrations of soluble cations in desulfurization gypsum on the whisker preparation. The low concentration of Na⁺ has a small effect on the calcium sulfate hemihydrate whiskers and barely affects the morphology and surface smoothness of the whiskers. The content of K⁺ is suitable to be 3% (mass fraction) or below, and the higher content has a detrimental effect on the growth of calcium sulfate hemihydrate whiskers. Mg²⁺ makes the whisker surface more homogeneous and crystalline. And the trace amount of selective adsorption of Al³⁺ has no effect on the whisker length-to-diameter ratio. Similar to K⁺, Fe³⁺ also has the optimal concentration, which is lower than 2 mmol/L. Unlike the cations mentioned above, Cu²⁺ is not from the raw material, but is an additional ion introduced in the doping of the appropriate amount of Cu²⁺ is conducive to the formation of whiskers with a smooth and uniform surface.