A cruise through the western sea area of the Taiwan Strait was carried out by the R/ V Dong Fang Hong in December, 1987. Eight anchored and 10 not anchored stations were set up. Over 25 time-series current observations were made at each station and CTD (Conductivity-temperature-depth) measurements were made at 5 anchored and 10 not anchored stations. Based on the measured data, fine-structures and step-like vertical structures of temperature and salinity were analysed, and a tentative wintertime current structure in the Taiwan Strait was described. A cruise through the western sea area of ​​the Taiwan Strait was carried out by the R / V Dong Fang Hong in December, 1987. Eight anchored and 10 not anchored stations were set up. Over 25 time-series current observations were made at each station and CTD (Conductivity-temperature-depth) measurements were made at 5 anchored and 10 not anchored stations. Based on the measured data, fine-structures and step-like vertical structures of temperature and salinity were analyzed, and a tentative wintertime current structure in the Taiwan Strait was described.