The lower stratospheric polar temperature and the eddy heat flux in spring for the past 50 years were investigated based on NCEP/NCAR reanalysis data. Both polar temperature and the eddy heat flux show significant variations in the year-to-year and the decadal time scales. Year-to-year variation of the polar temperature in March at 70 hPa is highly correlated with the eddy heat flux in February and March around 65°N, and this correlation explains most of the total variation of the polar temperature and eddy heat flux in the lower stratosphere. However, the decadal variation of the polar temperature is closely related to that of eddy heat flux near 70°N. Examining stationary and transient eddy heat fluxes separately, we showed that the year-to-year variation of the lower-stratospheric polar temperature in March is highly correlated with the stationary eddy heat flux, whereas the decadal-scale variation of the lower-stratospheric polar temperature is governed by the transient eddy heat flux. Temperature changes in the Southern polar temperature in spring are compared with those in the Northern hemispheric spring.