The invention relates to a casting formingmethod for producing dielectric ceramic. Barium titanate powders, dispersants, agarose and deionized water are mixed through ball milling according to a certain proportion; experiment on the rheological property is carried out on the obtained suspension liquid after ball milling for certain time, and casting is carried out under the room temperature; and green bodies obtained by casting together with molds are put in a drying oven of 90 DEG C. The method has the advantages that firstly the defects of the traditional forming method are overcome, the gel casting technology is adopted for forming, and novel environment-friendly and non-pollution nontoxic gel system agarose is used, great improvement is made in regulating the gel technology, the gel forming time is controlled through changing the using amount of the components of a gel system, the gel temperature, and the like, so that forming in short time can be realized, and the settlement of suspended solids is reduced to obtain evenly formed ceramic green bodies with little defect. Compared with other methods, the invention has the advantages of moderate reaction conditions, simple technological operation, non-toxicity, no pollution, high forming quality of green bodies, small internal stress and small cracks, so that the dielectric ceramic has a broader application prospect in the high voltage field.