The oxide compositions (OCs) model is established for discussing the chromatic aberrations of a gradient refractive index rod lens. The chromatic aberrations for ${\mathrm{Na}}^{+}/{\mathrm{Li}}^{+}$ , ${\mathrm{K}}^{+}/{\mathrm{Cs}}^{+}$ , and ${\mathrm{K}}^{+}/{\mathrm{Tl}}^{+}$ ion exchanges are discussed based on the OC model and the Huggins–Sun–Davis (HSD) model. Theoretical results indicate that the function value mainly depends on base glass properties and the nature of exchanging ion pairs, and rarely depends on the quantity of ion exchange. Experimental results show that the chromatic aberrations using the OC model have smaller errors than with the HSD model. The estimating average errors between the OC model and the HSD model are $-0.051$ , $-0.0067$ , and 0.0047 for the ${\mathrm{K}}^{+}/{\mathrm{Tl}}^{+}$ , ${\mathrm{Li}}^{+}/{\mathrm{Na}}^{+}$ , and ${\mathrm{K}}^{+}/{\mathrm{Cs}}^{+}$ ion exchanges, respectively.