Propargyl methanesulfonate (PMS) is chosen as an electrolyte additive to study the interfacial performance between the electrolyte and spinel lithium titanate (Li4Ti5O12, LTO) electrode. The result displays that PMS can improve cyclability of Li/LTO cell. Very interestingly, a solid electrolyte interface (SEI) film is formed above 1.0V in the voltage range of 3.0–0V. The observations are explained in terms of PMS include triple-bonded compounds and SO3. The triple-bonded compounds were able to produce a characteristic SEI with dense and low impedance, which can effectively suppress the decomposition of electrolyte, HF generation and LiF formation upon cycling. The SO groups may acts as the weak base site to hinder the reactivity of PF5. Accordingly, the incorporation of PMS into the electrolyte can remarkably enhance the cyclic performance of the Li/LTO cell.