The East Asian winter monsoon (EAWM) and Siberian high (SH) were both stronger than normal during the 2017/2018 winter, with significant intraseasonal variation. The geopotential height anomalies of midhigh latitude of Eurasia were mainly occupied by meridional circulation, with strong Ural high, and westward East Asian trough. The 2017/2018 winter was marked with frequent cold air processes, low temperature in northeasten China and abnormal warmer climate in Tibetan Plateau. Diagnostic analysis of possible mechanism for strong EAWM in 2017/2018 winter indicated that, subject to the modulation of warm phase of Pacific Decadal Oscillation (PDO), the influence of La Ni〖AKn~D〗a was comparatively weak. Meanwhile, the weak polar vortex of Northern Hemisphere, and continuously warm SST in north Atlantic, both associated with the strong EAWM in 2017/2018 winter.