Sardinops melanostictus and Scomber japonicus, as the main associated species in the northwest Pacific Ocean, are of great scientific significance for the management and sustainable use of fishery resources to study their potential habitat distribution and differences in response to environmental changes in this area. The fishery data of S.melanostictus and S.japonicus in the northwest Pacific Ocean from May to November in 2017-2021 were used, combined with sea surface temperature (SST), sea surface salinity (SSS), sea surface height (SSH), chlorophyll-a (Chl.a), eddy kinetic energy (EKE), and water temperature at different depths (50, 100, 150, 200 m) to construct a maximum entropy model.According to the response curves of the two to the key environmental factors of each month, the inter-month changes of the key factors on the potential habitats of S. melanostictus and S. japonicus were obtained, and the map of potential habitat distribution from May to November for S. melanostictus and S. japonicus was stimulated. The key factors affecting the change of suitable habitats from June and August to October were SSH, SST, and Chl.a, and their suitable ranges were not much different. The results show that the potential habitat changes of S. melanostictus and S. japonicus are consistent with the actual operating location, and with the increase of months, and they all show a trend of moving first to the northeast and turning back in the southwest direction, and their potential habitat positions overlap widely in each month. The key factors affecting the change of suitable habitat in May, July and November are different. The key factors affecting the change of suitable habitat in May, July and November are different, and the key factors of S. melanostictus are SSH, EKE, SST, the key factors in July are SSH, SST,Chl.a. The key factors in November are EKE, SST, Chl.a, while the key factors of S. japonicus are SSH, EKE, Chl.a in May, and the key factors in July are SST and Chl.a,SSS, while the key factors in November are SSH, SST, Chl.a, and the suitable range of environmental factors varies from month to month. In addition, as the number of months increases, the optimal habitat area of S. japonicus gradually decreases northward, with a minimum area in July and November, while the optimal habitat area of S. melanostictus tends to increase, extending to the area north of 37° north latitude in November. The study showed the changes of SSH, SST and Chl.a have an important impact on the distribution of potential habitats of S. japonicus and S. melanostictus in the northwest Pacific Ocean, and EKE and SSS are the main causes for the difference in the distribution of potential habitats.