The invention relates to a flow control device for a tundish of a slab continuous caster and manufacturing method thereof. The flow control device comprises a turbulent flow controller, a slag weir and a slag dam, wherein the upper edge of the slag weir is higher than the normally poured liquid steel highest liquid surface of the tundish but lower than the working surface of overflow port coating materials of the tundish, the slag weir and the slag dam are arranged in vertically staggered mode, and a through hole is respectively arranged at two ends of the slag dam. The centre distance a between the slag weir and the turbulent flow controller is 400-600mm, the centre distance b between the slag dam and the slag weir is 300-400mm, and the distance y between the working surface of overflow port coating materials of the tundish and the edge of the tundish is 120-160mm. The turbulent flow controller is of a structure made of combined composite materials, and the slag weir and the slag dam is respectively formed by molded pouring materials through casting molding in the intermediate temperate sintering process. By aid of the flow control device, injection residues of the tundish of slabs are reduced by more than 25% on year-on-year basis, service life of the flow control device is prolonged by one time on year-on-year basis, and continuous casting refractory material production cost is reduced by more than 30% on year-on-year basis.