Summary: Nylon‐6/Na+‐montmorillonite (MMT) nanocomposites (NNNs) are synthesized by a hydrolyzed ring‐opening polymerization. At a loading of only 2 wt.‐% MMT, the tensile modulus, the flexural modulus, and the heat distortion temperature of the NNNs exhibit increases of nearly 20%, 60%, and 63 °C, respectively. Compared with that of neat nylon‐6, the temperature of the main α‐relaxation (Tα) of the NNNs is shifted 3.6 °C toward higher temperatures and two β‐relaxation peaks are observed. Another interesting phenomenon is that there is a new melting peak (at about 206 °C) for the NNNs.