Flash devices for a space optical remote sensor are selected as researching samples. Start with the circuit structure of the devices

the total dose effects(TDEs) and invalid mechanism in space are analysed. It is considered that the ionization effects make the threshold voltage of transistors in devices drift. The continuous drifting arouses the control circuit and memory cells invalid. And the control circuit becomes invalid first than the memory cells. With the TDEs

the accumulation of trap charge makes the static current and dynamic current increase. According to the radiation experiment using 60Co γ source

the invalidation threshold of these devices is between 15k Rad(si) and 20k Rad(si). The analyse to TDEs and invalid mechanism of Flash devices is also proved by the experiment results. Finally

some radiation harden methods are put forward such as N modular redundancy

check coding and cold backup.