The seawater temperature density meter is a special instrument for measuring the density and temperature of seawater. It is mainly divided into two types, with a length of 20 cm and a length of 26 cm. The density range of 20 cm in length is 1.000-1.060 (accuracy 0.002), the temperature range is 0-40°C (accuracy of 1°C); the density measurement range of 26 cm in length is (1.000-1.040, accuracy is 0.001), the temperature range is 0-40℃ (accuracy 1℃).