In this study, we used the latest 30 years of wind and global wave field datasets of the European Center for Medium Range Weather Forecasting Reanalysis Interim (ERA-Interim) recorded from 1982 to 2011 to conduct statistical analyses of a 10-m wind field, significant wave height, mean wave period, and mean wave direction. Furthermore, we defined a method for calculating their seasonal variabilities. We determined that the significant wave height and mean wave period both have obvious seasonal variation and that the Northern Hemisphere ocean wave has greater variability than that of the Southern Hemisphere except for the Indian monsoon region. We then used wave age to determine the distribution of the wind sea and swell. The results indicate that the swell strengthened in the eastern part of the ocean and was dominant of the swell in the whole ocean. At last, we found obvious change in the distribution of swell in spring and summer.