Objective This paper studies on bio-impedance characteristics of malignant gliomas and brain tissues, then explores the characteristic electrical parameters and provides a fundamental basis to discriminate gliomas and normal brain tissues.Methods An in-vitro impedance sensor is designed based on four-electrode method.The impedance measurements on 10 cases of nude gliomas and brain tissues are performed using Princeton impedance analyzer VersaSTAT3 and then impedance spectrum characteristic curves are analyzed quantitatively from 20Hz to 250kHz.According to the electrochemical impedance spectroscopy principle, in vitro equivalent circuit model for glioma and brain tissues is established and the simulation with ZSimpWin is carried out to study the characteristics of glioma on impedance circuit model.Results Impedance magnitude varies oppositely as the frequency increases from 20Hz to 250kHz.Impedance spectrum curves around 200Hz and 50kHz have two slopes, respectively.And the slope scale for gliomas is less than that for normal brain tissues.There are two time constants in the imaginary-real plot and that can be expressed by equivalent circuit model.The parameter R1 in the circuit for glioma is significantly different from that for brain tissues.Conclusions The gliomas and normal brain tissues can be discriminated quantitatively by slope value of impedance spectrum curve.In addition, R1 in the equivalent circuit model can be viewed as an index to distinguish gliomas from normal brain tissues.The technique proposed in this paper provides a new method to detect and discriminate the gliomas from other normal tissues in cancer research.