The invention discloses a spanner head structure and a spanner. The spanner head structure has an opening groove for accommodating a fastening piece, and a slide piece capable of moving in a depth direction is arranged on a first side wall of the opening groove; a stop structure for stopping the slide piece is formed on the spanner structure; when the spanner head structure forwards rotates by surrounding the fastening piece, the slide piece can be abutted against a clamping stop surface of the stop structure to clamp the fastening piece with a second side wall so as to screw the fastening piece to perform the fastening or releasing operation; and when the spanner head structure reversely rotates by surrounding the fastening piece, the slide piece outwards moves far from the stop structure, and the clamping stop surface is gradually far from the second side wall to release the fastening piece, so that the spanner head structure freely rotates to be reset without being influenced by the fastening piece. The forward and reverse rotating actions are continuously and circularly operated, and the screwing action on the fastening piece can be continuously performed, so that the ratchet spanner function is realized, and the use is convenient. The smaller size can be realized. The whole structure is simple and skilful; and the practicability is high.