The invention relates to a mould used for manufacturing a breathing mask. The mould comprises a left forming mould and a right forming mould which can be face-to-face folded with each other, wherein a left cavity and a right cavity are respectively arranged in face-to-face folded walls of the left forming mould and the right forming mould; the left forming mould and the right forming mould can beface-to-face folded with each other, thereby forming an air blowing hole; the depth of the left cavity is different from the depth of the right cavity; embedded blocks which can be face-to-face folded with each other are respectively arranged in the left cavity and the right cavity; embedded edges which can be face-to-face folded with each other are respectively arranged at the peripheral edges of the left cavity and the right cavity; exhaust pipelines are respectively arranged in the left forming mould and the right forming mould; a left shaping mould and a left burr-removing mould are arranged at the left side of the left forming mould in turn; and a right shaping mould and a right burr-removing mould are arranged at the right side of the right forming mould in turn. The mould used for manufacturing the breathing mask is suitable for the manufacturing of a polyvinyl chloride breathing mask.