Provided are a non-contact palmprint authentication method and device and a portable terminal, which are applied to a portable terminal comprising a camera and an illuminating lamp. The method comprises: enabling a camera when a palmprint authentication flow is started, maintaining a working state of an illuminating lamp to be set as an illuminating mode when external illumination is insufficient so as to provide light supplement output for the camera； selecting a new frame of image from a video stream output by the camera as a candidate image, and acquiring a current state parameter set of the camera regarding the candidate image, and judging whether each state parameter in the set satisfies preset criteria corresponding to the parameter, and if they are all satisfied, then outputting the candidate image as a comparative palmprint image matching the palmprint； and performing user authentication by matching the comparative palmprint image with one or more pre-recorded standard palmprint images. The present invention can effectively improve the output quality of a comparative palmprint image so as to improve the performance of the non-contact palmprint authentication technology.
