Abstract: This paper is the second report of a research project concerning the characteristics and evolution of the general circulation in recent ten years. The amplitude and the phase angle are calculated by means of 4-term harmonic analysis for the monthly mean 500 mb hight along the 55°N and 35°N lat.from 1951 to 1960. According to the spectral distribution and phase angle, the seasonal variation of the general circulation is discussed.The conclusions are the following:(1)There is a pronounced seasonal course in the change of amplitudes of first and third harmonic.But this seasonal trend of the first and third harmonic at same latitude is opposite.The seasonal trend of the first or third harmonic at 55°N and 35°N lat. is also opposite. No clearly seasonal variation is revealed for the second harmonic. (2)The change of phase angle shows a regular seasonal course except for second harmonic at 55°N lat.(3) The variation of spectrum from 1951 to 1960 shows that the seasonal variation is different from year to year, but the general trend is the same for all years.(4) The characteristics of the spectrum of transitional seasons are clearly distinct from those of summer and winter, therefore the natural synoptic seasons may be clearly defined. The begining and ending as well as the length and character of the seasons vary from one year to another.(5) The weather anomaly in China has a close connection with the pattern of ultra-long waves in northern hemisphere. This may be shown by examples of July 1954 and 1959, as well as February 1957 and 1960.