Among various solid electrolytes, the NASICON-type Li1+x AlxTi 2−x(PO4)3 (LATP) solid electrolyte is one of the most attractive alternatives due to its high ionic conductivity and chemical stability. However, the limited ionic conductivity and interfacial stability with anode/cathode are the bottleneck of LATP electrolyte. In this study, we introduce transition metal dichalcogenides (TMDCs) of MoS2 in LATP structure during synthesis, and the properties are characterized. The ionic conductivity is increased after MoS2 incorporation, whereas the MoS2 structure is not detectable on XRD patterns. The chemical structures are analyzed by XPS, and we have tried to investigate the chemical stability of the samples. In addition, we have tried the cell performance with assembling the symmetry cells. This result shows that MoS2 incorporation could be an effective approach for realizing the LATP solid state lithium ion batteries.