Time-resolved pair distribution function (PDF) analysis is performed to clarify the formation mechanism of Li PS sulfide solid electrolytes in liquid phase synthesis with acetonitrile (AN), tetrahydrofuran (THF), and ethyl acetate (EA) solvents. This aims to clarify the relationship between their formations and lithium ionic conductivity. A complex is formed between the precursor of the sulfide solid electrolyte and each solvent during the liquid phase synthesis. The ratio of the solvent to the electrolyte is 3.03 in THF solution. The formation speed of precursors of sulfide solid electrolytes increases in the order AN < THF < EA solution, which is the same order as the lithium ionic conductivity. Thus, the correlation between the ionic conductivity and the formation rate of the precursor of the sulfide solid electrolyte might be related to the stability of the complex formed between Li PS and the solvent during liquid phase synthesis. 3 4 3 4