Provided are a radiotherapy device and system. The device includes: a fixed machine frame, a rotary machine frame, an imaging device and a treatment couch disposed on a side of the fixed machine frame. The treatment couch can move away from or close to the fixed machine frame along a first direction. The rotary machine frame is rotatably connected to the fixed machine frame provided with a treatment source; and the imaging device includes a ray emitter and a detector which are disposed oppositely, the ray emitter and/or the detector are/is disposed on the fixed machine frame, and rays emitted by the ray emitter are received by the detector after passing the affected part of patient, for capturing images of the affected part of the patient. The imaging device and the radiotherapy device are integrally designed, thereby effectively improving the locating accuracy of radiotherapy device, and improving effects of radiotherapy.