The latest version of the third generation spectral wave model, WAMC4, is adopted for the long-term hindcasting of wave climate for the East China Sea. The model is driven by the NCEP reanalysis wind data spanning the period of 1950—2009. A 2-level nested downscaling framework, covering the Northwest Pacific Ocean and the East China Sea is established to simulate both wind and swell waves. The model result is validated against field data at Lianyungang and Lengjiasha. Based on the long-term modelling results, the temporal and spatial wave distributions of the area are obtained. The results suggest that the mean significant wave height decreases significantly from south to north, and its contours are consistent with the coastline. For the seasonal wave distribution, the mean significant wave height is the largest during winter and smallest during spring and summer. Furthermore, by comparing the significant wave field of 5% cumulative probability with mean significant wave field, the quantitative relationship between the two is obtained for different sea areas.