Abstract: This paper deals with the activity of the medium-high latitude westerly wind belt, the subtropical high pressure and the Monghala (孟加拉) pressure trough before strong earthquakes in Yunnan province. With the aid of statistical experiments, a feature of abrupt change of the meridianal circulation index and the pattern of spatial distribution of the surface pressure field has been found. It gives a possibility of short-range prediction of strong earthquakes, M7 in Yunnan.