【Abstract】Objective To characterize the electrodiagnostic features of hereditary neuropathy with liability to pressure palsies（HNPP）. Methods Eight patients from three families with HNPP and their relatives underwent routine nerve conduction studies, and contrasted with 30 healthy subjects. Routine electrodiagnostic tests included median, ulnar, radial, tibial and proneal motor and sensory nerve conduction study. Results 76 motor nerve and 58 sensory nerve conduction velocity of the patients were tested. ①It showed broad and diffuse nerve conduction abnormalities，superimposed by conduction block, ulnar nerves at the elbow were more common than proneal nerves at the fibular head.②Distal motor latencies were significantly prolonged in 92.1% of the nerves, All the median and peroneal nerves with both symptomatic and asymptomatic patients were prolonged.③The abnormal rate of motor nerve conduction slowing was 63.2%, the most common affected nerves were median and peroneal nerve.④The abnormal rate of sensory nerve conduction slowing was 89.6%, with sural and median nerve affected more.Conclusion Neurophysiological examination is crucial to diagnose clinically suspected HNPP patients. It is useful to screen the family members of HNPP patients, as well as early detection, early prevention.②HNPP is characterized electrophysiologically by a generalized neuropathy, superimposed by focal conduction block, prolonged distal motor latency, obvious in median and proenal nerves. The slowing of sensory conduction was more severe than motor conduction.