The invention relates to a sector pouring ladle with fan-shaped slag back plate. The sector pouring ladle with fan-shaped slag back plate comprises a fan-shaped area and a slag discharging zone, wherein the slag discharging zone is arranged at the upper end of the fan-shaped area; the fan-shaped area is composed of a sprue gate arc, a triangular straight baffle, a triangular bottom baffle, a ladle bottom baffle and a fan-shaped baffle plate which are sequentially connected; a slag back plate is also arranged in the fan-shaped area and the sprue gate arc is circular arc protruding from the direction of the slag outlet with the center of the sector pouring ladle rotating center; the slag back plate and the fan-shaped baffle plate are all circular arcs with sector pouring ladle rotating centers as the center; the arc of the fan-shaped baffle plate occupies an arc of 40-70 degrees round the radius of the fan; the radius of the slag back plate to the center of the fan pack is 1 / 5-1 / 3 of the radius of the fan-shaped baffle plate to the center of rotation of the sector pouring ladle; the angle between the arc of the slag back plate and the rotating center of the sector pouring ladle is larger than the angle between the arc of the fan-shaped baffle plate and the rotating center of the sector pouring ladle. The sector pouring ladle with the fan-shaped slag back plate can ensure that the iron liquid flowing out of the unit at any time interval is equal in quantity at the same speed; the liquid iron that flows out of the sector pouring ladle is purified; the probability of casting defects caused by slag is reduced.