The embodiment of the invention discloses a three-dimensional display depth adjusting method and device based on multi-frequency decomposition. The method comprises following steps of determining a target image with a to-be-adjusted depth; obtaining a Gaussian pyramid corresponding to the target image based on a Gaussian filter function, wherein the Gaussian pyramid is composed of space frequency bands with different depths; obtaining frequency bands specific to a logarithm domain according to the space frequency bands in the Gaussian pyramid through a frequency band difference function; obtaining backup 3D display images according to the logarithm domain frequency bands through a reduced low frequency function; obtaining a to-be-displayed 3D display image with the adjusted depth based on the backup 3D display images and a difference value function, and finishing depth adjustment. Through application of the embodiment of the invention, targeted adjustment is carried out to the different depth values; and changes of depths can be perceived.