Conductivity-temperature-depth system (CTD) is one of the world’s most widely used instruments in physical oceanography. In this paper, oceanographic data acquired by three different types of CTD (37Coastal, 304Plus, and CTD48) were compared and analyzed. These CTDs were carried in the subsurface buoy placed in the Yellow Sea by Institute of Oceanology, Chinese Academy of Sciences in 2014. Results showed that the minimum pressure and temperature difference were both between 37Coastal and CTD48, while the highest correlation coefficient in salinity was between 37Coastal and 304Plus. The stability of the pressure, temperature and conductivity data acquired by those tree CTDs showed that pressure data of 37Coastal were the best of all. Three CTDs had similar stability on temperature data while the salinity data of 37Coastal were consistent with that of CTD48.