Abstract: Single event effect（SEE） in floating gate memories are reviewed.SEE in the control circuit and the memory cell are analyzed and discussed in detail.This paper points out that the control circuit is the key part in the memory’s radiation effect and the heavy ions’ irradiation degrade the data retention characteristics of the floating gate memories.The possible mechanism of charge loss in memory cell after radiation is discussed.Finally,it is pointed out that nanocrystal memories have good tolerance to heavy ions’ irradiation.