To compensate for the lack of sub-surface environmental data of the fishing ground, this experiment analyzed the vertical temperature and salinity structure at the fishing points using the gradient-dependent optimal interpolation and Argo profiles in the Kuroshio-Oyashio Confluence region.The reliability of the constructed results was verified by theoretical testing and comparison with in-situ observation. The results showed that the maximum root mean square errors of the temperature and salinity were less than 1 ℃ and 0.4 compared to Argo profiles. Furthermore, the absolute deviation of temperature and salinity from the "Songhang" survey data is less than 0.25 ℃ and 0.27, respectively.Analysis discussed the vertical temperature and salinity structure and the relationship with the squid CPUE.The results indicated the suitable temperatures for squid at the 5m were 16 ℃ and 14 ℃ in August and October 2018. And the suitable temperatures decreased to 9-12 ℃ at the depth of 50m.The statistical relationship between temperature and squid CPUE conforms to an exponential function under a certain curvature. Additionally, it was observed that there are significant thermoclines at the fishing points. The greater the variation in thermocline intensity, the greater the randomness of the squid CPUE. When the thermocline intensity at the fishing points is around 0.4 ℃/m, the squid CPUE is relatively stable. Regardless of the month, higher CPCEs are located in low-salinity areas.This study provides a new approach for establishing long-time-series and quasi-real-time environmental data of fishing ground. That will offer the necessary data support for deep research on fishery dynamic mechanisms.