An experiment study of heat transfer through condensation in vertical sine-shape fluted tube is made. The relationship of the local heat transfer and the vertical coordinate is discerned. When we derive the practical relationship, a new characteristic constant L_c is proposed. Then we use the L_c to display the new dimensionless vertical coordinate (z/L_c) to replace the original dimensionless vertical coodinate (z/L) obtained through the tube length used by other researchers.