The high and low pass filter analyses of the atmatmospheric motion in the process of a blocking for five days show that the genesis,maintenance and collapse of the atmospheric blocking depend chiefly upon the slow variable waves whose time scale is more than five days. At the stage of the genesis and maintenance of the blocking, the high-frequency waves which last less than 5 days show east-west contraction and north-south extension when they propagate eastward into the jet stream branch. Calculations of the energy transfer between different time-scale components indicate that the interaction between the slow variable waves and the high-frequency waves is the important mechanism of the genesis and collapse of the blocking pattern. And the time scale of the blocking is governed by the quasi-two-week oscillation of the atmosphere.