The membrane flux curve characteristics of cross-flow hollow fiber membrane in direct contact membrane distillation (DCMD) were investigated under various experimental conditions. The results indicate that the increase of feed inlet temperature diminishes the impact of the feed concentration on the flux. Both a low feed inlet temperature and a high feed flow rate lead to a high membrane thermal efficiency. Various operating parameters interact with each other in DCMD process. The feed and distillate inlet temperatures influence the flux mainly by changing temperature difference between two sides of the membrane. The feed flow rate influences the flux mainly by changing the temperature polarization at feed side. The distillate flow rate influences the flux mainly by changing the residence time of the distillate in hollow fiber membrane as well as by impacting the temperature polarization in a certain extent. Consequently, different flux curve characteristics are formed respectively under different operating conditions. This study is helpful to understand the DCMD characteristics. (C) 2012 Elsevier B.V. All rights reserved.