Abstract: In this paper, 285 fast events at 2545 MHz, 2645 MHz and 2840 MHz recorded during the 21st and 22nd solar activity cycles are analysed. Various kinds of the fast events are found during that period. It is found that the fast fine structures (FFS)observed during the two solar maxim are very different, for example, the discrete and isolated spikes, the clusters of the crowded spikes, the spikes superimposing on the noise background, and the phenomena of absorption occurring in solar cycle 21, and events with more narrow bandwidths, frequency drifts, polarization and the quasi-periodic oscillations occurring in solar cycle 22. In addition, the rate of FFS occurrence are also different for the two cycles. Some events associated with solar flares are analysed, too.