When reversal occurs on a register of CAN bus in a satellite, the communication between digital devices is often hindered, and even the whole bus will work abnormally. Currently, there is not an effective method to detect and locate which register in CAN bus generates reversal, that the only thing we could do was closing firstly then opening all the nodes of the satellite one by one, so designed a novel method called three safeguard and classified the influence of reversal on register of CAN according to continuance. The first is only changing numerical value. The second is affecting communication for a whole. The last is affecting communication longterm. The method three safeguard can save those satellites which taken reversal on register of CAN. Through simulation verification, this method can offer an innovative technology to solving the trouble caused by reversal on register of CAN.