Ternary mixed solvents solution of water-hydrophilic/hydrophobic organic solvent is an example of a two-phase separation, mixed solvent solution system. Upon temperature change, the homogeneous solution (single-phase) changes to the heterogeneous solution (two phases), generating upper (organic solvent-rich) and lower (water-rich) phases in a batch vessel. When the ternary mixed solution is fed into a microspace, the solvent molecules are radially distributed in the microspace under laminar flow conditions, generating inner and outer phases. Herein, this is termed the tube radial distribution phenomenon (TRDP). In this study, the dimensionless number, Weber number, of the inner and outer phases in the TRDP process was estimated for the water-acetonitrile-ethyl acetate and water-acetonitrile-chloroform systems. Further, as an attempt, a relationship between the Weber number and TRDP formation was examined for the two model systems in this experiment. TRDP was observed in both systems when the Weber numbers of the organic solvent-rich and water-rich phases were different. However, an either excessively large or small difference in the Weber numbers did not instigate TRDP. TRDP formation was compared with an annular flow formation using the immiscible mixed solvent solutions.