The present invention provides an antibody or antibody fragment thereof for a targeted cytomembrane voltage-gated sodium channel α subunit Nav1.9. The specific binding target is a S3-4 ring of a voltage sensor paddle of a domain II of the voltage-gated sodium channel α subunit. The antibody or antibody fragment thereof is able to inactivate a voltage sensor valve, to make sodium ions unable to enter nerve cells normally, thereby achieving the effect of treating and relieving pains.