Yb (III) shows complex behavior of coordination dissolution and precipitation in carbonate solutions, but the properties of CO32− coordination and hydration to Yb (III) in the solution have not been explicated. In this work, the dissolution rule of Yb (III) with CO32− concentration has been studied. The radial distribution function and the coordination number of CO32− and H2O to Yb (III) were calculated by molecular dynamics simulation, and the complex ion form of Yb was obtained. The ultraviolet−visible spectrum and the ionic structures of Yb (III) complex ions were geometrically optimized and calculated by using density functional theory. Then, the experimental ultraviolet−visible spectra and density functional theory results were combined to verify the molecular dynamics calculations. The results indicate that Yb (III) undergoes precipitation in low-concentration carbonate solution, but, in high-concentration carbonate solution, Yb (III)’s carbonates will undergo dissolution. The main reason for the dissolution of Yb (III)’s carbonates is the coordination effect of CO32− on Yb (III); the coordination of carbonate on Yb (III) occurs with a CO32− concentration range of 0.4~2.0 mol·L−1. Yb (III) mainly exhibits [Yb·9H2O]3+ hydrated form in the aqueous solution, while, in the carbonate solution, [Yb·9H2O]3+ is converted into [Yb(CO3)2·5H2O]− complex. [Yb(CO3)2·5H2O]− complex is the main ionic form in high-concentration carbonate solutions. The analysis method in this work provides guidance for understanding the coordination and hydration characteristics of oxyacid radicals to rare earth elements.