Example methods for processing a user interface of an application and a related device are disclosed. One example method includes: if a difference between a size of a current display region and a size of a target display region satisfies a target condition, obtaining first layout information corresponding to the user interface when the user interface is displayed in the current display region, where the first layout information is obtained based on target layout information used when the user interface is displayed in the target display region, and when the user interface changes from a layout manner indicated by the target layout information to a layout manner indicated by the first layout information, a size change ratio of a first composition element is different from a size change ratio of a second composition element.