The invention provides an arc-shaped bleacher plate mold and a manufacturing method thereof. The arc-shaped bleacher plate mold comprises a base, wherein a left side mold and a right side mold of which the cross sections are arc-shaped are arranged on the upper surface of the base; a bottom mold is arranged between the left side mold and the right side mold, is inverted U-shaped, and is equipped with a top plate, a left side plate and a right side plate; two side edges of the top plate as well as the cross sections of the left side plate and the right side plate are also arc-shaped; the radians of the two side edges of the top plate as well as the cross sections of the left side plate and the right side plate are the same as those of the left side mold and the right side mold; an arc-shaped left bottom mold is arranged between the left side plate and the bottom of the left side mold; an arc-shaped right bottom mold is arranged between the right side plate and the bottom of the right side mold; the radians of the left bottom mold and the right bottom mold are the same as those of the left side mold and the right side mold; a bottom mold bracket is arranged below the top plate; a left stiffening plate is arranged between the bottom mold bracket and the bottom of the left side plate; a right stiffening plate is arranged between the bottom mold bracket and the bottom of the right side plate; end molds are arranged at two ends of the bottom mold bracket; and a casting space is formed among the end molds, the left side mold, the right side mold, the bottom mold, a suspended mold,the left bottom mold and the right bottom mold in an encircling manner.