The invention relates to a method for raising the steepness of a silicon carbide high-energy ion implantation thick mask. The method comprises the steps of (S1) cleaning the surface of a silicon carbide material, (S2) depositing a first layer of ion implantation thick mask capable of blocking high-energy high-temperature ion implantation at the surface of the silicon carbide material, (S3) uniformly applying photoresist on the surface of the first layer of ion implantation thick mask and developing a selective ion implantation region window by using the photolithographic development technology, (S4) etching the first layer of ion implantation thick mask from the selective ion implantation region window until reaching the surface of the silicon carbide material, (S5) removing the photoresist, (S6) depositing a second layer of ion implantation thin mask, and (S7) performing full surface etching on the second layer of ion implantation thin mask to obtain the ion implantation thick mask with smooth and steep side walls. According to the method, the steepness of the ion implantation thick mask can be significantly raised, and the ion implantation mask preparation process and removal process are simplified.