An electric conductivity probe was designed to study local void fraction of gas-liquid two-phase flow in a rectangular helically coiled channel. Reliability of the electric conductivity probe was verified by measuring length of Taylor bubble at various gas superficial velocity and by comparing it to visualization measurement. A suitable threshold value was determined for signal processing. Effects of liquid and gas superficial velocities on local void fraction distribution were investigated at three regimes of bubbly

slug and annular flow. The experimental results show that local void fraction distribution of gas-liquid two-phases in helically coiled channel is asymmetric parabola

which the asymmetry is dependent on flow regime and liquid superficial velocity.