Japan Meteorological Agency performs 7-day sea ice forecasting in Southern Okhotsk Sea with numerical dynamic and thermodynamic models. The current JMA computation uses a continuum model for the ice dynamic process. In this paper, The Distributed Mass/Discrete Floe Model, which considers the discrete characteristic of sea-ice and well simulates the ice edge location in short computational time, was introduced and the thermal mixing process of sea water was improved. In addition, for a higher accuracy forecasting, the current grid size of 12.5×12.5km was reduced down to 5×5km and improvement of sea-surface current data was discussed.