Abstract: In this paper we have analysed the burst data at 3.2cm and 10cm during the period January to December,1979.The bursts that the peak flux density increase-ment (S/S)≥50% amount to 25 and we find that there are oscillations on the preburst recording curves of all the 25 bursts,the period of the oscillation is from a few seconds to ten seconds and the amplitude is about 1% of the solar undisturbed component.Such a oscillation usually precede burst for a few hours or a few days,but for outstanding burst it will be disappeared for tens minuts or a few hours before burst,and without this phenomenon in smaller,impulsive and shorter complex bursts.Thus the oscillating characteristics may be a process of energy accumulation in flare region.