Abstract: Spatio-temporal distribution of chub mackerel Scomber japonicus is strongly susceptible to climate variability. In this study, a weighting-based habitat suitability index (HSI) model was established to assess the impacts of Pacific Decadal Oscillation (PDO) on habitat range and distribution of S. japonicus in the East China Sea (ECS) using vertical water temperature at depths of 2.5 m, 25 m and 50 m. Results showed that the optimal HSI model selected from ten weighting scenarios can yield reliable predictions. Correlation analysis revealed a significant negative relationship between the PDO index and water temperature anomaly at different depths. The water temperatures at three different layers on the fishing ground of S. japonicus tended to be low in the warm PDO phase and high in the cold PDO phase, respectively. The range of suitable habitats and its spatial distribution exhibited large differences between the warm and cold PDO regimes. During a warm PDO phase, vertical water temperature became cool, and the monthly preferred water temperature at each depth for S. japonicus shifted southeastward. Consequently, habitat quality dramatically decreased, and suitable habitat ranges also reduced and moved southeastward. Conversely, in a cool PDO phase, with the warmer vertical water temperature and northwestward shift of the preferred water temperature, the suitable habitats enlarged and migrated in the same direction. Our findings indicate that the PDO produced significant impacts on habitat range and distribution of S. japonicus in the East China Sea.