Abstract: The neutron radiation effects on three different sizes of super deep submicron SOI NMOSFET (0.25 μm, 0.18 μm and 0.09 μm) were studied. The mechanisms of neutron radiation damage were analyzed. The output characteristic parameters of the three types of devices changing with different 1 MeV equivalent neutron fluences and the influence of the process parameters of the devices on neutron radiation damage were simulated. The results of simulation and experiment agree well.