The anomalously low Surface Air Temperature (SAT) and the corresponding atmospheric circulation anomalies in the Northern Hemisphere during the winter (DJF) of 2009/2010 are investigated. Surface Air Temperature Anomalies (SATA) were zonally distributed with a "positive-negative-positive" pattern from tropical to polar region which was characterized by positive SATA in low latitudes, negative SATA in middle latitudes, and positive SATA in high latitudes. The coldest SATA were located in Eurasia and eastern USA, and in some parts SATA exceeded -4 ℃. SAT in middle latitudes decreased by nearly 1 ℃ compared to the average of the last 15 years, and in Eurasia SAT even decreased by -8 ℃. The anomalous feathers of horizontal circulation was that, both sea level pressure and geopotential height fields exhibited positive anomalies in high latitudes and negative anomalies in low latitudes, associated with anticyclonic circulation anomalies in high latitudes and cyclonic circulation anomalies in middle latitude, and both high levels and low levels exhibited this feather. The anomalous feathers of zonally mean meridional circulation indicated that, Ferrel cell was weakened, with anomalous ascending motion in middle latitudes and anomalous descending motion in high latitudes, at the same time, atmosphere temperature of troposphere in middle latitudes was anomalously low and that in high latitudes was warmer, with a stronger jet in subtropics and a weaker jet in the polar region. Composite and correlation analysis of the Northern Hemisphere Annular Mode (NAM) and SATA shows that, during positive (negative) phase of NAM, there was a positive (negative) band in middle latitudes, and it was most significant in Eurasia and eastern USA, with nearly 2 ℃ warming (cooling) in some regions. Analysis of air temperature equation shows that meridional temperature advection anomalies associated with anomalous meridional wind play a very important role in the variability of local temperature, and its distribution closely resembled the SATA in 2009/2010 winter. With composite and correlation analysis, the mechanism for the relationship between NAM and SATA is investigated. During the positive phase of NAM, the Ferrel cell is anomalously strong, the mass between two latitude zones exchanges, in sea level pressure positive anomalies is in middle latitudes and negative anomalies is in high latitudes, which forces southerly surface wind anomalies in the middle latitude. As a result, the meridional temperature advection is enhanced, which results in warmer SAT in middle latitudes. The situations is opposite during negative phase of NAM. The above-mentioned physical mechanism reveals that surface air temperature in mid-latitude is modulated by NAM as a natural variability.