The invention relates to the technical field of projection, and discloses a wearable projector and a focusing method and a projection method thereof. The focusing method comprises the steps of collecting the location information, in the projection center of the palm, of the wearable projector; determining the distance between the projection center and the wearable projector according to the set frequency and the collected location information, in the projection center of the palm, of the wearable projector; determining the focal distance of a lens set in the wearable projector according to the determined distance between the projection center and the wearable projector; adjusting the focal distance of the lens set according to the determined focal distance of the lens set. After focusing of the lens set is finished by adopting the focusing method, when the wearable projector carries out projection on the surface of the palm, a processing module can control an adjusting device to adjust the focal distance of the lens set according to the set frequency, when the position of the fingers changes, the focal distance of the lens set can be adjusted in time, and therefore the stability of definition of display pictures projected onto the surface of the palm by the wearable projector can be improved.