The utility model discloses a separation-preventing filling hole sliding plate of a dry-mixed mortar tank truck. The separation-preventing filling hole sliding plate comprises a conical plate body, wherein same arc-shaped gaps are formed in symmetric positions of two sides of the plate body, a plurality of material holes are uniformly formed in the plate body, and two reinforcing rings are welded on the inner side of the plate body. According to the separation-preventing filling hole sliding plate, the same arc-shaped gaps are formed in the symmetric positions of two sides of the plate body, the plurality of material holes are uniformly formed in the plate body, and thus materials can be effectively prevented from separating and charged sufficiently.