Physical Precusor of An Extraordinarily Large Flare of 1986 February 4

The precusory features of an extraordinarily large flare(4B) which ejrupted on February 4,1986,during the minimum of solar activities are analysed by means of the observed data of the photosphere,chromosphere and radio noise storm,which originated form the solar corona,in this paper.This may be useful to those who work on the physical prediction of flares and the physical mechanisms of large flares during the minimum of solar activities.