Objective As the central in cognitive functions, the power of theta rhythms (4—12Hz) received more attention. Here, the relationship between theta power and electrical features was investigated in order to know more about the physical meaning of theta power. Methods By using the method of finite element method (FEM) in COMSOL Multiphysics (FEMLAB), the field potentials (FP), derived from the oscillatory dipole currents (4-8Hz), were computed in different conducting medium, and then theta power values of FP were calculated. Results (1) Theta power was decreased with the increase of electrical conductivity, however not decreased with the enhanced anisotropy. (2) It was possible that the level of theta power in anisotropic medium might be greater than that in isotropic medium. (3) Theta power was affected by both the amplitude and the frequency of dipole current. Conclusions Theta power was related to both the conducting medium and the activity of dipole current.