Ionic liquids with halide anions were prepared and the dependency of halide anions on the $SO_2$ solubility of ILs was investigated. The study shows that the $SO_2$ solubility of ionic liquids lies in the range 1.91~2.22 $SO_2$/ILs mol ratio. $SO_2$ solubility in ionic liquids with varying halide anions follows the order Br > Cl > I. Theoretical investigation was also conducted at the B3LYP level using the Gaussian 03 program. From the theoretical consideration of the interaction between $SO_2$ and [EMIm]X (where X = Cl, Br, and I), it has been proposed that primary interaction of halide occurs with $C_2$-H of the imidazolium and S of $SO_2$. Experimental results further shows that the absorption and desorption process of $SO_2$ in ILs was reversible by the three cycles of the absorption at $50^{circ}C$ and desorption at $140^{circ}C$. The reversibility of $SO_2$ absorption was confirmed by FT-IR studies.