This study is devoted to some aspects of mid-and high-latitude low-frequency pertur-bation(LFP)in the context of 1984～1986 ECMWF/WMO gridded data.Evidence suggests that the LFP’s equivalent barotropic structure can be described in terms of a"structure parameter"(the ratio of low-frequency barotropic kinetic energy to low-frequency kinetic energy total); the high-value areas of the energy are closely associated with the zonal asymmetry and meridional shear of westerly jet; the LFP’s propagation is marked by salient locality and confluence/difluence,and can be interpreted by the counterclockwise loops of the central-Pacific lowfrequency cyclone/anticyclone couplet(β-gyres); the Eastern-Asian longitudes at which westerly jet finds its entrance is the key region of interaction between NH mid-and low-latitude LFP’s, on one side,and between bihemispheric counterparts; low-frequency vortex activity of mid-and high-latitude bears an intimate relation to the change in blocking,on the other.