A seat turnover structure for a child dining chair comprises a seat, a front chair leg and a rear chair leg, a sliding clamping assembly is arranged between the front end of the seat and the front chair leg, and a rotating shaft is arranged between the rear end of the seat and the rear chair leg. And the rear end of the seat is overturned on the rear chair leg through a rotating shaft, and the front end of the seat is supported and clamped on or separated from the front chair leg through a sliding clamping assembly during overturning. According to the utility model, the structure is improved;a user can quickly and conveniently turn over the seat on the rear chair leg or position the seat on the front chair leg; according to the dining chair, the occupied position of the dining chair is effectively reduced, a user can turn over and store the chair when not using the dining chair, meanwhile, the chair can be positioned on the front chair legs when being opened, the problem that a childis injured due to the fact that the chair cannot be positioned and turned over again when in use is solved, and the practicability is high.