This work aims to improve the application of Ti-6Al-4V alloy in maritime field. Fast multiple rotation rolling (FMRR) technique was applied to create a nanostructure layer on Ti-6Al-4V surface. The mechanical properties were also investigated. Then the FMRR samples were plasma nitrided at a temperature as low as 550 °C with the duration of 4 h. The microstructure and properties of FMRR samples and nitrided samples were characterized by high resolution transmission electron microscopy (HRTEM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), microhardness testers and optical microscopy (OM). Results indicated that FMRR can cause surface nanocrystallization with the average grain size of 65~90 nm, 45~70 nm and 20~40 nm, when the duration was 15 min, 30 min and 45 min respectively. Twins, low angle grain boundaries and high-density dislocations were observed in the surface of FMRR samples. The SAED pattern was composed of continuous diffraction rings. No new phase was induced in the top surface of Ti-6Al-4V by FMRR treatment. The diffraction peaks of FMRR samples were broader compared with the original samples. The microhardness was improved from 325HV in the matrix to about 453HV in the top surface layer. The nitrided layer in the top surface of FMRR sample after plasma nitriding included a bright compound layer and a transition layer. Conclusion:FMRR treatment provides additional energy and structures for the subsequent nitriding at lower temperature, thus leading to an increase in nitriding rate and a roughly 100 μm thick.