The remote-sensing experiments of CH4 in the fall and the winter of 2005 spent about two weeks with open-path Fourier transform infrared spectroscopy (OP-FTIR) in Beijng. The two-week records of CH4 concentration were examined by means of the time-series analysis to elucidate the seasonal cycle. The weekend effect was analyzed. Turbulence and photochemical condition were the main factors to influence CH4 concentration. Correlations between CH4 concentration and meteorologic variety were also discussed such as wind speed, wind direction, temperature, relative humidity. It is revealed that wind speed and wind direction can affect CH4 concentration. The origin of methane is discussed, and it's found that the origins and wind direction are important factors to influence CH4 concentration.