The present application provides methods and devices for determining an action or an action part, and generally relates to the field of wearable devices. A method disclosed herein comprises: in response to detecting a motion of a first part of a body of a user, acquiring, using a photoelectric sensor, target Doppler measurement information of the first part or a second part corresponding to the first part; determining target velocity related information corresponding to the target Doppler measurement information; and determining the first part or the action according to the target velocity related information and reference information, wherein the target velocity related information comprises target blood flow velocity information or target blood flow information. The methods and devices provide a new scheme for recognizing an action and/or an action part.