The invention relates to a novel carcass pressing device of a tire forming machine.The carcass pressing device is used for pressing a carcass ply, an inside liner and padding rubber.The carcass pressing device comprises an upper pressing roller, a middle pressing roller and a lower pressing roller which are respectively used for pressing the padding rubber, the inside liner composite layer and the carcass ply, wherein the middle pressing roller can be divided into a left section, a middle section and a right section, and the three sections form radian identical with the radian of the connector of an inner liner composite part according to certain angle.By the arrangement, the pressing problems, caused by the radian of the insider liner composite part, of existing pressing devices are solved.