The feasibility of applying C4D technique to void fraction measurement of gas-liquid two-phase flow is investigated in this paper. As a preliminary research, void fraction measurement under stratified flow is studied. Conductance of two-phase fluid are obtained by a new C4D sensor, and then used to measure the void fraction in 15mm i.d. pipe. An empirical correlation between void fraction and normalized conductance is developed. Thus, the void fraction can be determined by this empirical correlation with the obtained conductance. The experiment results show that applying C4D technique to the void fraction measurement of gas-liquid two-phase flow is feasible. The measurement results of void fraction are satisfactory, and the maximum absolute error of void fraction is less than 0.03.