Disclosed are a magnetic resonance imaging system protecting method and device, and an automatic shutoff testing method. The protecting method includes a), providing expected safety parameters; b), after the magnetic resonance imaging system starts scanning corresponding to initial sequence information, collecting actual sequence information in the process of scanning; c), according to the actual sequence information, calculating actual safety parameters; d), judging whether the actual safety parameters do not exceed the expected safety parameters or not; e), if yes, continuing to execute scanning corresponding to an initial sequence; f), if not, stopping scanning. The device comprises an input module used for inputting the expected safety parameters, a collection module used for collecting the actual sequence information, a calculation module used for calculating the actual safety parameters according to the actual sequence information, a judgment module used for judging whether all of the actual safety parameters do not exceed the expected safety parameters or not, and the control module is used for controlling to continue to execute scanning if yes and to stop scanning if not. By the protecting method and the protecting device, safety of a scanning object in the actual process of scanning can be effectively guaranteed.