The effects of Li+ addition on the sintering and microstructural evolution of cordierite were analyzed. As nucleating agent, the Li+ additive decreased the expansion coefficient and dielectric constant. The doping of Li+ was found to block the phase transition from μ-cordierite to α-cordierite and increase sintering temperatures. The effect of Li+ on the activation of cordierite can be attributed to the nucleation of cordierite. Too much Li+ will inhibit the cordierite crystallization and encourage amblygonite crystallization. Cordierite powders were prepared by sol-gel processing.