Abstract: The prediction accuracy of the overload retardation effect on fatigue crack growth （FCG） is closely related to the formula for tie plastic zone adopted by each retardation model. Hence, in order to express more rationally the behavior of fatigue crack growth process and the continuity of the stress state transformation （from plane strain to plane stress mode）, the coefficient α in the formula for the plastic zone used in the Willenborg and Maarse models can be expressed as the following:a=6/1+2S whereS is the fraction of the stress part in a fracture surface. Meanwhile, it was found that the material constants C* and n* in the formula of the Maarse model can be substituted by C and n obtained from the constant amplitude loading tests.From the above mentioned modification of the Willenborg and Maarse models, it is recognized that the modified models can be applied more successfully and conveniently to the life prediction for Ti- 6A1-4V alloy under a single tensile or a series of single tensile overloads. The results calculated with the modified models were found to be fairly consistent with the experimental data.