In this work, we comprehensively explore hot carrier degradation (HCD) in multiple-fin SOI FinFETs with both short channel length and long channel length, and demonstrate that the degradation mechanism in short channel device is different from that of long channel device. The hot carrier degradation in short channel length device under long stress time is dominated by oxide charge. Meanwhile, the hot carrier degradation is aggravated by self-heating effect (SHE).