In this work, using the sea temperature data on the western Yellow Sea during 1959-1995, the main features of long-term, stage and interdecadal variations in Qingdao Cold Water Mass (QCWM) strength were studied by using regression analysis and maximum entropy method. The QCWM'S interannual change and possible causes were discussed using the air temperature data in North China. The results showed that the QCWM strengthened during 1959-1975 and weakened during 1976-1995; and that the stage change in the QCWM'S strength displayed regular low-frequency oscillation. The interannual changes in the water mass strength were associated with the ENSO cycle, and were affected by winter (February) air-temperature changes in the coastal area of the northern Shandong Peninsula.