Abstract: Based on the 10 years global reanalysis database from the MASNUM Wave Forecast System, the climate characteristics of the wave distribution in the North Indian Ocean are analyzed. Due to the monsoon domination in this region, the waves in summer are heavier than in winter. As the spacial distribution shows, there are heavier waves forced by stronger wind in the west of the ocean than in the east, and the heaviest in offshore of Somalia and in the Gulf of Aden. The capability and property of the MASNUM Wave Forecast System are verified using the SWH (Significant Wave Height) observational data from the Jason 1 satellite altimetry. It is learnt from the verification that the overall RMS (Root Mean Square) error of the forecasted SWH is about 0.5m. The errors in the 24 hour forecast result are the least, being less than either in the 48 or the 72 hour forecast one. And the forecast results in winter are more precise than in summer. The probability distributions of the errors in the forecast results are further discussed.