The Stark spectra of Yb atom with m= 0 in the vicinity of n-18 wereobtained by using two-step excitation of π π polarized lasers in the applied electric field from o V/cm to 1514 V/cm. The method based on diagonalization of the energy matrix with the Stark effect was applied to Yb atom. The theoretical Stark map agrees with experimental Stark map. It is observed that Stark manifold exhibits linear structure with theincrease of the electric field in the low-field region. A large oscillator-strength transfer between 1P1 state and nearby Stark manifold occurs in the course of anticrossing. The dependence of level-structure on quantum effects is discussed.