The invention relates to a method for preparing a reverse osmosis membrane by using 1-methylimidazole as an aqueous phase additive. The aromatic polyamide composite reverse osmosis membrane is prepared by taking the 1-methylimidazole as an aqueous-phase solution additive and adopting an interfacial polymerization method. A support membrane is infiltrated into an aqueous-phase solution containing 1-methylimidazole, so that the support membrane is fully infiltrated by the aqueous-phase solution; the membrane is infiltrated into an oil-phase solution containing trimesoyl chloride to carry out interfacial polymerization reaction so as to form an aromatic polyamide separation layer; and heat treatment is performed on the membrane to obtain the aromatic polyamide composite reverse osmosis membrane. The disclosed method has the advantages that the preparation process is simple, the cost is relatively low, the implementation is easy, and the prepared aromatic polyamide composite reverse osmosis membrane has the characteristics of high flux and high rejection rate. In addition, the disclosed method can also provide references for preparation of other high-performance interfacial polymerization separation membranes.