The angular distribution of the electron ejected from Eu atom 4f76p1/28s auto-ionizing state, whose energy range covers from 60600.0 cm-1 to 61860.2cm-1, has been investigated in use of the velocity mapping imaging technique. Eu atom is stepwise excited from the 4f76s2 8S7/2 ground state to the 4f76s8s 8S7/2 Rydberg state through the 4f76s6p 6P5/2 intermediate state, then excited to the 4f76p1/2(J=3)8s and 4f76p1/2(J=4)8s auto-ionizing states further by using the three steps isolated-core-excitation method. The value of the total angular momentum is calculated by the excitation scheme and the selection rule, the energy range and properties are deduced from the energy, angular momentum and parity conservation in auto-ionization process. The ejected electron, which is the production of the auto-ionization process, is focused and imaged by the electron lens. The kinetic energy of it is resolved by the position sensitive detector, and by using the velocity mapping imaging technique, mathematical transformation and calculation for ejected electron angular distribution is carried out. Simultaneously, by tuning the wavelength of the third dye laser, the propensity of the angular distribution and the anisotropy parameters following the variation of the photon energy has been obtained, and the physical essence has been discussed.