Abstract: Changes in the intensity and central location of the polar cell strongly influence the evolution of mid-high latitude weather and climate systems, making it important to understand their interdecadal variations and underlying causes. This study investigates the long-term variation characteristics and possible mechanisms of the NPCW (northern polar cell in winter) during 1959–2022. The analysis is based on the meridional and regional mass stream functions derived from ERA5 reanalysis data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF). The results reveal pronounced interdecadal variability in the NPCW. Both its intensity and central location shifted around 1987 and 1997, and the NPCW generally follows a pattern of “strong and southward–weak and northward–strong and southward.” Interdecadal changes in quasi-stationary planetary wave activity in the Northern Hemisphere winter were the key factor dominating these phenomena. The amplitude of the quasi-stationary planetary wave in the Northern Hemisphere winter increased at high latitudes but decreased around 40°N–50°N during 1987–1997, compared with that during 1976–1986. This pattern altered lower-tropospheric pressure systems, inducing southerly wind anomalies over the mid-high latitude North Atlantic, which weakened NPCW intensity. Concurrently, the upward propagation of quasi-stationary planetary waves into the stratosphere over high latitudes along the polar waveguide was reduced, decreasing the convergence of Eliassen-Palm (E-P) fluxes in the lower stratosphere over high latitudes of the Northern Hemisphere. Thus, the polar front jet was enhanced through planetary wave-mean flow interaction. The Arctic Oscillation (AO) then shifted to a positive phase, and the polar vortex strengthened. Meanwhile, anomalous cooling in the Arctic troposphere coupled with anomalous warming in the mid-latitudes increased the mean meridional temperature gradient. This enhanced gradient promoted eddy activity over the mid-high latitudes of the North Atlantic and North Pacific, driving a poleward shift of the NPCW’s ascending branch and thus altering the circulation’s central location. Conversely, during 1998–2008, opposite anomalies in quasi-stationary planetary wave activity in the Northern Hemisphere winter led to northerly wind anomalies in the lower troposphere and a weakened mean meridional temperature gradient, causing the NPCW to strengthen and shift southward compared with the previous period.