Abstract: Provided is a fully-spherical radiation therapy system. The fully-spherical radiation therapy system includes a multi-degree-of-freedom robot, a linear accelerator and a double-image-guided positioning mechanism. The double-image-guided positioning mechanism includes four ray sources and two ray detectors, and the four ray sources include a first ray source, a second ray source, a third ray source and a fourth ray source. An intersection of two beams emitted by the first ray source and the second ray source is a low-level treatment center, an intersection of two beams emitted by the third ray source and the fourth ray source is a high-level treatment center, and the low-level treatment center and the high-level treatment center form a fully-spherical treatment space for multiple treatment nodes of a spherical center.