Summary Due to the increasing need for drinking water in the world, various membrane processes have been developing significantly over the past several years. The process of membrane distillation is one of the non‐isothermal processes that cause steam to pass from the membrane due to the difference in temperature and the resulting difference in vapor pressure. Due to the lack of precision in the amount of flux and thermal efficiency in various operating conditions the membrane distillation process still needs development. This article attempted to examine the effects of flowrate, temperature, and module length on the performance of the membrane distillation process using computational fluid dynamics simulation and experiments design method. Since each of these parameters interacts with other parameters, the design of experiments method was used for numerical modeling of flux and thermal efficiency. The results showed that increasing flowrate, inlet feed temperature, and decreasing length of the membrane module increase the water flux and thermal efficiency. Numerical flux modeling results show that temperature (T), module length (L), and interaction module length‐temperature (L‐T) parameters have the most influence on flux and module length (L), temperature (T) and quadratic relation of module length (L2) parameters have the greatest effect on thermal efficiency, respectively. CFD simulation of Direct Contact Membrane Distillation (DCMD) process and numerical modeling the effect of flowrate, feed temperature, and module length parameters on flux and thermal efficiency by design of experiments method.