A method for monitoring user health, a device for monitoring user health, and a terminal for monitoring user health are provided. A method for monitoring user health includes: acquiring an illuminance of an environment, where the environment is an environment in which a user is currently located acquiring a first pupil size when the user is located in the environment correcting the first pupil size on the basis of the illuminance to acquire a second pupil size comparing the second pupil size with a reference pupil size to determine a change rate of a pupil size of the user and determining a health state of the user on the basis of the change rate of the pupil size. The problem that the terminal device may not monitor users health comprehensively can be solved and the effect of monitoring users health comprehensively can be achieved.
