This disclosure relates to display adjustment methods and head-mounted display devices. The head-mounted display device includes: first and second display modules; a first adjustment unit for triggering the first display module to enter a diopter adjustment mode and/or an interpupillary distance adjustment mode and for triggering the second display module to enter a non-adjustment mode; a confirmation unit for receiving a confirmation signal indicating that the first adjustment unit has completed the adjustment; a second adjustment unit for triggering the second display module to enter the diopter adjustment mode and/or the interpupillary distance adjustment mode and for triggering the first display module to enter the non-adjustment mode after the confirmation unit has received another confirmation signal. Independent display adjustment is achieved between the first and second display modules in the head-mounted display devices using the methods in this application, thereby providing an adjustment mode adapted for different user visions.