The present application relates to the technical field of vehicle parts, and in particular to a trim mounting method, an engine hood assembly, and a vehicle. According to the trim mounting method, a trim is mounted to a vehicle part comprising an inner plate and an outer plate by means of a screw and a kennel structure for packaging the screw, comprising: arranging a through hole that allows pass through of the kennel structure on the outer plate; arranging a screw hole corresponding to the through hole on the inner plate; mounting the trim onto the vehicle part along a first direction, so that the kennel passes through the through hole and the screw packaged by the kennel structure passes through the screw hole; and fixing a screw bolt with a nut in a second direction. According to the method, a thin trim limited by thickness can be mounted onto a vehicle part; moreover, a stamping molding defect of the vehicle part can be avoided; furthermore, the trim is mounted onto an inner plate of the vehicle part, so that the arrangement, on the inner plate, of a mounting space required for mounting the trim onto an outer plate is avoided and the strength of the inner plate can be increased.