This study presents the longitudinal distribution of thermospheric density around the terminator (in the dawn and dusk sectors), using observations collected by the atmospheric density detector onboard the Chinese satellite APOD (Atmospheric density detection and Precise Orbit Determination) from 2017 to 2018. The APOD observations show a significant relative longitudinal variation of thermospheric density with global maxima (Δρ_rmax) near the geomagnetic pole, especially in the winter hemisphere. The annual maximum of Δρ_rmax appears in the Southern Hemisphere around the June solstices and reaches 26.3% and 39.6% at dawn and dusk, respectively. Compared with at dawn, Δρ_rmax occurs at a higher latitude with a larger value at dusk. The auroral heating and meridional wind might play an important role in the longitudinal variation of thermospheric density. We further compare the APOD observations with the NRLMSIS 2.0 model predictions under low solar activity condition. The NRLMSIS 2.0 model reproduces similar longitudinal variations to the observations, with hemispheric asymmetry and local time difference.