The invention relates to a simulation and planning system for intraoperative radiation therapy and to a method allowing said system to be used for treatment studies, simulation, planning, training and recording, which system generally comprises a central processing unit or computer (1) for management and control and software-based communication with the rest of the devices and the user; one or several monitors or screens (2) for displaying images and peripherals responsible for gathering data relating to the actions performed by said user, a deformation simulation module for the virtual simulation of the deformation produced in the organs and tissues during the process; algorithms for instantly calculating the radiation dose applied during the radiation therapy treatment simulation and means for recording all the activities carried out and generating a full dosimetry report.