The utility model relates to a cap with projection function, including the cap body and the brim of a hat, the micro -projector is installed to the brim of a hat, the internal signal line of having buried underground of cap, and the one end of signal line is pegged graft with the signal input interface of micro -projector, and the other end has the suitable data interface who pegs graft with mobile device data interface. The utility model discloses cap with projection function presss from both sides the dress in brim of a hat top or lower end with the micro -projector, can present the projection on the person of wearing curtain or other planes at the moment of the image in the mobile device or video, has increased the picture size, and it is tired to have lightened the eye to projected mode has addd the interest. The micro -projector is installed in the brim of a hat for detachable, power cord and data line bury underground with the internal portion of cap, be favorable to the washing of cap. Except the usage data line carries out data transmission, the utility model discloses can also adopt wireless transmission's form to carry out the projection with image or video, it is more convenient to use.