The invention relates to a hydrophobic associated polymer intrinsic viscosity determining method. The hydrophobic associated polymer intrinsic viscosity determining method includes the following steps that step S10, a hydrophobic associated polymer solution is prepared, cyclodextrin and a sodium chloride solution are added to the hydrophobic associated polymer solution to prepare a to-be-tested sample solution; step S20, a sodium chloride solution is added to the to-be-tested sample solution, and the mass concentrations C, specific viscosities eta sp and reduced viscosities eta sp/C of the to-be-tested sample solution and the mixed solution are respectively measured; step S30, a excel graphical method is used for determining the intrinsic viscosity [eta]; step S40, the intrinsic viscosity [eta] is inspected. The hydrophobic associated polymer intrinsic viscosity determining method has the advantages that the characteristics of having hydrophobic cavities of the cyclodextrin are utilized to include hydrophobic groups and shield a hydrophobic associating effect, and the influence on intrinsic viscosity determination of the hydrophobic associated polymer of super-molecular aggregation formed by the associating effect is avoided; the measuring accuracy is high, the cyclodextrin has no surface activity, the measuring accuracy is not affected even if the quantity is excessive.