A projection method of a wearable projecting device comprising carrying out the following steps at a set frequency:: acquiring position information of a projection center of the wearable projecting device on a palm;: determining a distance between the projection center and the wearable projecting device according to the acquired position information of the projection center of the wearable projecting device on the palm of a hand;: determining a focal length of a lens set in the wearable projecting device according to the determined distance between the projection center and the wearable projecting device;: adjusting the lens set according to the determined focal length of the lens set; and: controlling the wearable projecting device to conduct projection, characterized in that: between two successive executions of the step of adjusting the lens set according to the determined focal length of the lens set, the wearable projecting device is controlled to project at least two frames of images, and within a duration of the at least two frames of images, the method further comprises: acquiring definition information of an image projected on the palm after one frame of the at least two frames of images is projected; determining whether the definition of the projected image is within a predetermined range or not according to the acquired definition information of the projected image, and if the definition is not within the predetermined range, determining focal length correction information during the period of projecting the next frame of the at least two frames of images, and correcting the focal length of the lens set according to the determined focal length correction information.: acquiring position information of a projection center of the wearable projecting device on a palm;: determining a distance between the projection center and the wearable projecting device according to the acquired position information of the projection center of the wearable projecting device on the palm of a hand;: determining a focal length of a lens set in the wearable projecting device according to the determined distance between the projection center and the wearable projecting device;: adjusting the lens set according to the determined focal length of the lens set; and: controlling the wearable projecting device to conduct projection, characterized in that: between two successive executions of the step of adjusting the lens set according to the determined focal length of the lens set, the wearable projecting device is controlled to project at least two frames of images, and within a duration of the at least two frames of images, the method further comprises: acquiring definition information of an image projected on the palm after one frame of the at least two frames of images is projected; determining whether the definition of the projected image is within a predetermined range or not according to the acquired definition information of the projected image, and if the definition is not within the predetermined range, determining focal length correction information during the period of projecting the next frame of the at least two frames of images, and correcting the focal length of the lens set according to the determined focal length correction information. acquiring definition information of an image projected on the palm after one frame of the at least two frames of images is projected; determining whether the definition of the projected image is within a predetermined range or not according to the acquired definition information of the projected image, and if the definition is not within the predetermined range, determining focal length correction information during the period of projecting the next frame of the at least two frames of images, and correcting the focal length of the lens set according to the determined focal length correction information.