Abstract: By using synthesis, EOF analysis, numerical simulation and the other methods, this paper investigate the intraseasonal climate characteristics of two typical persistent flow patterns, pattern E (there are a longwave ridge, trough, ridge over the Ural Mountains, Lake Baikal, the Sea of Okhotsk, respectively) and pattern C (the positions of trough and ridge is opposite to pattern E’s), over Eurasian middle and high latitudes in summer. The main conclusions are as follows: (1) The deviation of the actual frequency from the theoretic normal distribution probability of the circulation pattern index shows a bimodal feature, i.e., the actual frequency of patterns E and C is more than the theoretical value.(2) The indices averaged over 1959-2000 presents obviously an intraseasonal staggered variation in resemblance to the northward advance of the subtropical high over the western Pacific and summertime rain belt in China. The result of numerical simulation shows this feature too. (3) The obvious contrast between pattern E and pattern C exists not only over Eurasian middle and high latitudes but also over the other areas of the Northern Hemisphere. The occurrence and change of these persistent anomalous circulations are closely correlated with the positive and negative phases of the East Asia－Pacific (EAP) pattern, as well as the two modes of the South Asia high and the western Pacific subtropical high. It is a new focus for understanding the interaction of the systems over different latitudes of Eurasia and its cause of formation.