In this paper, an anomalous temperature dependence of hot carrier lifetime has been extensively studied for the first time. We have found that the hot carrier lifetime does not increase linearly with increasing stress temperature. On the contrary, around 90°C, hot carrier lifetime decreases with increasing stress temperature. Using the charge pumping method, we found that interface state distribution after hot carrier stress at high temperature is less localized. Since interface state on channel region is more effective than that on LDD region, lower lifetime at high temperature can be explained. This anomalous behavior causes significant impact on device reliability while operating at high temperature.