It is essential to efficiently extract travelling wave signal for travelling wave based protection and fault location. Because the conventional capacitive voltage transformer（CVT） is not able to accurately transmit transient high frequency signal， a method for extracting voltage travelling wave signal is proposed. Using the tip capacitance of CVT or current transformer， the circuit which extracts voltage travelling wave signal is designed and analyzed. The output responses of extraction circuit for different frequency bands， different fault inception angles and different grounding resistances are simulated respectively with EMTDC. Theoretical analysis and simulation results demonstrate that this method can efficiently extract transient high frequency signals and properly reflect the characteristics of voltage travelling wave of primary side within specified frequency band.