The extraction of gold in membrane extractors was theoretically investigated. Extraction of gold in the form of Au(CN)(2)(-) in a solution of n-heptane and synergistic extractants of LIX79+TOPO was studied. The membrane extractor consists of three sections: the tube side, the membrane, and the shell side. Conservation equations were derived for Au(CN)(2)(-) in the membrane module and were numerically solved based on finite element method. Simulations were conducted through solving the momentum and mass transfer equations simultaneously. It was indicated that as the feed flows within the tube side, it moves into the membrane due to the concentration difference, and then gets swept by the moving extractants within the shell side. The distribution of solute concentration in the membrane contactor was obtained. Simulation results showed increasing the feed flow rate reduces the extraction efficiency, while doing the same for the organic phase flow rate does not change the extraction efficiency.