Abstract: In this paper, we analysed the 50 hPa potential height anomaly field in the Northern Hemisphere using the EOF method. It is indicated that (1) there are several stationary circulation patterns in 50 hPa field of the Northern Hemisphere, and the stable fitting precision of EOF, (2) there is a obvious “see-saw” phenomenon between high latitude and middle latitude in the 50 hPa potential height anomaly field of the Northern Hemisphere, (3) the quasi-biennial to quasi-triennial oscillation and quasi-four month oscillation of 50 hPa circulation field in the Northern Hemisphere exist obviously, and the QBO phenomenon of equatorial stratosphere is also verified, and (4) as compared between the 500 hPa and 50 hPa field, the first and second characteristic vectors of potential height anomaly field have the similar spatial distribution, but EOF expansion in the stratosphere whether the stability of fitting precision or the convergence is better than that in troposphere.