The daily thunderstorm data from the Capital Airport (Beijing) from 1958 to 2007 are used to perform the analysis of the temporal variations of summer thunderstorms, and the wavelet analysis is used to disclose its interannual and interdecadal variations. The results show that there was obvious daily variation in thunderstorm weather from July to September in the recent 50 years; there was a decline tendency in thunderstorm days, especially in July and August; obvious 1 to 2, 4 to 6, and quasi10 year oscillations can be found in summer thunderstorm days at the Capital Airport, among which 1 to 2 year oscillations are most significant; meanwhile,the quasi10 year oscillation is also obvious.