The invention relates to the manufacture technology of high manganese steel castings, in particular to a cutting method of a dead head of a high manganese steel casting. The cutting method includes the following steps: (1) ensuring that the temperature of the dead head of the casting is above 100 DEG C after demolding of the casting; and cutting off 1/2 to 3/4 of the dead head in a hot cutting method and ensuring that the distance between the cutting position of the dead head and a casting body is more than 15 mm and the temperature of the root portion of the dead head after cutting is no lower than 80 DEG C; (2) conducting water toughening on the casting and the remained dead head; (3) leading the temperature of the dead head to be above 100 DEG C after water toughening of the casting, and cutting off the remained dead head of the high manganese steel casting in a machining method or the hot cutting method; and (4) conducting hot treatment on the casting again after the dead head is completely cut off. The cutting method solves the problem that presently, cutting of the dead head of the high manganese steel casting in a plant is difficult and micro-cracks exist on the root portion of the dead head, and is applicable to the manufacture process of high manganese steel castings more than 500 Kg in weight and of various models and specifications.