The present invention provides an antibody or antibody fragment thereof for atargeted cytomembrane voltage-gated sodium channel a subunit Nav 1.9. Thespecificbinding target is a S3-4 ring of a voltage sensor paddle of a domain II of thevoltage-gated sodium channel a subunit. The antibody or antibody fragmentthereofis able to inactivate a voltage sensor valve, to make sodium ions unable toenter nervecells normally, thereby achieving the effect of treating and relieving pains.