Carbonic acid is a biological effector molecule with broad application prospects in skin care and skin disease intervention. The hydration conversion effect of carbonic acid precursor molecule CO₂ in aqueous medium is the key to the formation of carbonic acid, however, the factors affecting its hydration conversion have not been fully studied. Based on cosmetics, the effects of rheology modifiers, ionic strength, humectants, and emulsifiers on CO₂ hydration conversion in aqueous environment were studied respectively; the cytocompatibility and human efficacy of CO₂ minimalist formula system were discussed. The results show that the hydration conversion effect of CO₂ decreases with the increase of the viscosity of the rheology modifier; it decreases with the increase of the ionic strength; the enhancement of the polarity of the polyol molecule is beneficial to the hydration conversion of CO₂; the change of the molecular structure of the emulsifier affects the hydration conversion effect. In addition, the CO₂ medium system showed excellent cytocompatibility to human keratinocytes, and the minimalist formula system containing CO₂ lowered the skin pH, increased the skin moisture content, but increased the trans epidermal water loss rate. This research provides a research idea for the development of CO₂ products and provides theoretical and application support for CO₂ skin care applications.