The incidence of facial nerve palsy has always been relatively high, and its age of onset can be more widespread from childhood to old age. The diagnosis of the disease currently relies on symptoms and signs to determine the disease. The most important thing that many people want to clarify after getting sick is: Will this disease get better? To what extent? Neuroelectrophysiology can tell you the answer. Facial nerve conduction and transient reflex in neurophysiology can detect the electrical response of facial nerve motor fibers and trigeminal-facial reflex pathway, respectively. Facial nerve conduction is mainly observed for its latency and wave amplitude. After facial nerve injury, if demyelination is predominant, it will show a predominantly prolonged latency, and if axonal damage is predominant, it will show a reduced wave amplitude. However, not all facial nerve palsy can manifest as conduction abnormalities, and only when the damage is more severe will the above manifestations occur. The transient reflex is used to determine the site and degree of damage to the facial nerve and trigeminal nerve by the reflexes of the trigeminal nerve – the facial nerve – on both sides. Based on the results, the prognosis of facial nerve palsy can be determined. If the affected side is slightly lower than the healthy side, the prognosis is still good. If the corresponding waveform on the affected side is straight, the prognosis is often very poor. The frontalis, orbicularis oculi, and orbicularis oris muscle innervated by the facial nerve are less frequently operated by needle electromyography because it is, after all, an invasive test. After facial nerve damage, the features of loss of nerve can be demonstrated in the EMG of the corresponding muscles mentioned above. We neurologist clinicians, when receiving facial nerve palsy, if we have no idea whether it is recovered or not, we can make a judgment by electrophysiology.