Based on the cluster model with phenomenological alpha-core potential,alpha decay half-life of europium isotopes are investigated. The calculated results indicate that cluster model is more appropriate for europium isotopes than the Coulomb and Proximity Potential Model. In order to study the isospin effect of nuclear potential, we introduce the factor f, which is used to modify phenomenological alpha-core nuclear potential. Using the existing experimental data of alpha decay half-life, the values of factor f for europium isotopes are calculated. The results indicate that there is a strong linear correlation between f and isospin. And the correlation coefficients are also extracted.
