The ocean exists pycnocline characterized by abrupt variations in temperature and salinity, exerting significant hazards of rapid sinking or floating of underwater vehicles. Consequently, Conductivity-Temperature-Depth (CTD) data serve as vital environmental parameters for submarine navigation. These factors are increasingly utilized in the multi-sensor fusion navigation for underwater vehicles. Recently, the increasing accuracy of underwater navigation techniques introduces a growing demand for enhanced precise detection in CTD data. The necessitates enhancing the stability and accuracy of sensors and acquisition circuits, as well as optimizing data calibration methods. Traditional methods of collecting and calibrating CTD data are plagued by inadequate stability and low accuracy. To address these issues, a CTD data acquisition and calibration method based on the least squares approach is presented. The objective of the paper aims to enhance the measurement accuracy of CTD data, while simultaneously minimizing costs and design complexity, thus facilitating the practical engineering application. Compared to previous methods, the approach achieves a tenfold improvement in accuracy, satisfying the first-level metrological requirements outlined in JJG 763-2019.