Provided is an antibody or a fragment thereof, which can be specifically boundto an S3-4 ring of a voltage sensor paddle of a domain III of voltage-gatedsodiumchannel Nav1.9 .alpha. sub-unit, and is able to inactivate a voltage sensorvalve to keepsodium ions from entering nerve cells normally. Also provided is an epitopepolypeptide specifically bound to the antibody or the fragment thereof, apharmaceutical composition comprising the antibody or the fragment thereof,and ause of the antibody or the fragment thereof in preparing a drug for treatinganddiseases related to pains.
