The monomer-aggregate equilibrium Of four phenothiazine (PN) dyes, containing thionine (TH), methylene blue (MB), new methylene blue (NMB), and 1,9-dimethylmethylene blue (DMB), in the tungsten(VI) oxide (WO3) nanocolloid Solution has been investigated by means of UV-vis spectroscopy. Addition of PN dye into the WO3 nanocolloid Solution brought about significant changes in the absorption Spectrum, Suggesting the formation of H-type (Face-to-face fashion) trimer oil the WO3 nanocolloid Surface. The adsorptivity of PN dyes onto the WO3 nanocolloid surface was diminished by the raising the ionic strength, indicating the evidence of the electrostatic interaction between cationic PN dye and negatively charged WO3 nanocolloids. The detail analysis of each spectral data provided insight into the effect of molecular structure of PN dyes oil the adsorption and aggregation behaviors on the WO3 nanocolloid surface. Moreover, fit stiff measurement of PN dye aggregation using the centrifugal liquid membrane (CLM) technique revealed that the aggregation of PN dyes on the WO3 nanocolloid surface proceeded in a two-step three-stage (monomer --> dimer --> trimer) formation. The aggregation mechanism of PN dyes on the WO3 nanocolloid surface was discussed oil the basis of Kasha's exciton theory.