In this paper, an experimental investigation was carried out for the distribution characteristics of bubble contact areas in a full transparent narrow channel. The dimension of narrow channel was 2 mm x 10 mm x 250 mm, and the heating length was 200 mm which was the ITO coated glass. The deionized water was used as working fluid, and the bubble contact areas were observed with a highspeed camera from the bottom of heating wall. It was found that the density of bubble contact area was simultaneously affected by the nucleation rate and the coalescence rate for bubbly flow. Also, the fluctuation of bubble contact area density increased with increasing heat flux and decreasing mass flux, respectively. Moreover, the bubble contact diameter was well consistent with the distribution of Inverse Gaussian. Finally, the distribution parameters of nu and lambda were predicted, and the predicted results agreed well with the experimental results. (C) 2019 Elsevier Ltd. All rights reserved.