Two cores and ten surface sediment samples were taken in the western area of Mid-Pacific during the investigation from December 1978 to July 1979. According to the analysis of planktonic foraminifera and CaCO3 in the surface samples, the investigated area is divided into three different sediment regions. The initial depth of lysocline of this area is estimated at about 3500 m and the CaCO3 compensation depth (CCD) is 5000 m. The water depth of the sediment core at L2016 is 2705 m and it is located above the lysocline. The sediments belong to white plank-tonic foraminiferal ooze. The evolution of paleoclimate is studied according to the variation of the following three parameters: the abundance value of the species indicating warm of planktonic fo-riminifera, the solution index and the determination of the paleotemperature carve of δ13O. The age of 4.2 in-long core is estimated at about 300,000 years BP according to the extinct time of the pink shell G. rubra, and the comparison between cores. Two cores and ten surface sediment samples were taken in the western area of ​​Mid-Pacific during the investigation from December 1978 to July 1979. According to the analysis of planktonic foraminifera and CaCO3 in the surface samples, the investigated area is divided into three different sediments The initial depth of lysocline of this area is estimated at about 3500 m and the CaCO3 compensation depth (CCD) is 5000 m. The water depth of the sediment core at L2016 is 2705 m and it is located above the lysocline. The sediments belong to white plank-tonic foraminiferal ooze. The evolution of paleoclimate is studied according to the variation of the following three parameters: the abundance value of the species indicating warm of planktonic fo-riminifera, the solution index and the determination of the paleotemperature carve of δ13O. The age of 4.2 in-long core is estimated at about 300,000 years BP according to the extinct time of the pink shell G. rubra, and the comparison betwee n cores.