The invention provides a method for reconfiguring an RAM of a 1553B bus chip of a BC terminal of a spacecraft. The specific process comprises the steps of determining a fault degree through self-check when the RAM of the bus chip has an unrecoverable fault on orbit; adding a bus chip mode switching instruction, and then using a stack area and data block area combination different from that in a current mode according to the instruction, thereby finishing the reconfiguration of the bus chip; or creating a stack area and data block area setting instruction of the bus chip according to an actual fault condition, performing addition, and then forming a new stack area and data block area combination by using resources capable of being used yet in the chip according to the instruction, thereby finishing the reconfiguration of the bus chip; and if the fault still exists, adopting a measure of switching a BC terminal device to a standby device, and ending the RAM reconfiguration processing of the bus chip. According to the method, backup RAM area resources can be used to replace faulted RAM area resources according to the fault condition, and the RAM can continue to run normally through the reconfiguration.