The top portion of a continuous, atmospheric reactor for nylon-6 polymerization, where the reactants are being boiled and mixed together, is modelled by a continuous flow stirred tank reactor(CSTR). The polymerization mechanism of nylon-6 has been introduced, and the material and energy balances are solved by Newton-Raphson method. The numerical solutions under various conditions of the parameters involved in the reaction show that the feed water content has the greatest influence on the reaction temperature, water concentration and energy consumption. Keeping the reaction temperature and water concentration constant by reducing both the feed water content and the jacket temperature is the best way to save energy without any influence on the reaction characteristics. Also, it is shown that if the feed acetic acid content increases, both the conversion of monomer and the proportion of acetyl end-group increase, and this affects the degree of polymerization and polydispersity.