This letter investigates abnormal degradation behavior after hot-carrier stress in partially-depleted silicon-on-insulator n-channel metal-oxide-semiconductor field effect transistors. It is found that the hot-carrier-induced degradation under floating body (FB) operation is more serious than that under grounded body (GB) operation due to the floating body effect (FBE). Furthermore, the degradation is independent on temperature under GB operation, because impact ionization is virtually independent on temperature under large VD. However, the degradation under FB operation becomes less serious with increasing temperature. This is due to a smaller source/body PN junction band offset at a high temperature, which causes fewer accumulated holes at the body terminal and reduces the FBE.