Abstract:There were ten typhoon torrential rain events in North China during the midsummer from 1949 to 1996.Their maxima of total course rainfall (abbreviated to MTCR) each event were more than 400mm.By using the view point of the interaction between typhoon and westerly trough,weather patterns of these events have been classified.By practical experience,the typhoon trough,Hetao westerly trough,the high pressure of Japanese sea Bohai sea,SE wind jet at 850hPa over Shanghai area and the weak cold air intrusion into typhoon are to be considered as the weather pattern criteria.It is shown that only five of the ten events belong to the interaction weather patterns′ but the others aren′t.These five events took place in the first ten days of Aug.in 1950,1963,1975,1984 and 1996.Besides,the interannual variations in typhoon′s MTCR have been computed by the lag covariance power spectral analysis.It is shown that there are two periods.One is 11 yrs,the other is 31 yrs.And the 5 interaction weather pattern events mentioned above are the main components of the 11 yr period.According to the cross spectral analysis,there is a high coherence with high confidence at intervals of 11 years between the typhoon′s MTCR and the sun spots.Phase angle difference shows that the year of typhoon′s exceptional MTCR in general lags around 5 yrs behind the M year of the sun spots.