The invention discloses a vertically-separated support for oral cavity radiotherapy and a manufacturing method of the vertically-separated support. The vertically-separated support for oral cavity radiotherapy comprises a support body. The support body is a hollow shell. The external shape of the support body is matched with the intra-cavity shape, formed when a patient opens the mouth, of the oral cavity. The front portion of the support body is a fixed portion, and an upper surface shell and a lower surface shell of the fixed portion are provided with an upper dentition impression groove and a lower dentition impression groove respectively. The rear portion of the support body is a supporting tongue pressing portion, the upper surface of the supporting tongue pressing portion serves as a support palate surface, and the lower surface of the supporting tongue pressing portion serves as a support tongue surface. The fixed portion and the supporting tongue pressing portion are communicated through a ventilation channel. The oral cavity support is suitable for oral cavity jaw surface tumor radiotherapy, the exposure dose which endangers organs can be stably and effectively reduced, oral mucosa damage and taste damage generated in the oral cavity jaw surface tumor radiotherapy process are reduced, and compliance and quality of life are improved when the patient receives radiotherapy.