Abstract: Field programmable gate array (FPGA) is extremely susceptible to failures caused by high-energy particle radiation in space, thereby affecting the normal execution of on-chip tasks. At present, the triple modular redundance (TMR) method is usually used for fault-tolerant design. Although well fault-tolerant effect can be achieved, a large amount of resource expenditure is required. Especially when the radiation level is low, the implementation of TMR method for all tasks can aggravate the above problem of high resource overhead. In view of this, a method of FPGA fault tolerance based on dynamic self-adaptive redundancy is proposed. First of all, using the high sensitivity of on-chip block RAM (BRAM) to space particle radiation, the BRAM-based radiation level monitor is designed and improved to periodically monitor the radiation level of the space environment. Secondly, slack time of execution cycle and current radiation level are standard for evaluating the reliability levels of tasks, and then a task is used as a granular for dynamic self-adaptive matching redundancy strategy under different radiation levels to ensure the successful execution of on-chip tasks while avoiding high resource overhead. Simulation results show that the FPGA with this method has high reliability under different radiation levels. Compared with the popular FPGA fault tolerance method based on redundancy, the on-chip task completion is increased by 57.2% on average under the same radiation level.