Abstract: The diurnal variation of the atmospheric CH\-4 at the urban area in Beijing displayed a very clear cycle,generally with the lowest value being recorded in the daytime and the highest at night.It showed a large seasonal cycle with two peaks,one in later summer and the other in the winter.The peak in the winter was contributed mostly by anthropogenic methane sources.The concentration of atmospheric CH\-4 in Beijing increased rapidly at an annual rate of 0.82% from 1985 to 2000,with a mean of (1 883.4±73.0)nmol/mol.But the growth rate in the 1990s was lower than that in late 1980s.