The developments of efficient reverse osmosis (RO) membranes and their fabrication mechanisms are significant for water purification. Graphene oxide (GO) membranes show excellent stability and large permeance, but the large transport nanochannels make it difficult to be applied for RO desalination. Herein, a strategy, confined interfacial polymerization, is reported for preparing ultrathin polyamide (PA)-GO membranes with excellent performance in RO desalination. By making use of the adsorption of negatively charged GO with oxygen-containing groups to meta-phenylene diamine (MPD), the polymerization between MPD and trimesoyl chloride (TMC) at void regions of GO layer is carried out, which can refine the size of transport nanochannels. The resulting PA-GO membrane displays high salt rejection of 99.7%. Because of the 30-nm thickness of and the small amount of formed PA, the large permeance of 3.0 L m(-2)h(-1) bar(-1) is achieved. Moreover, the PA -GO membrane shows good long-term stability, high chemical stability and low fouling propensity.