The invention provides an LEU circuit switching method and device and a storage medium. The method includes: during power-on start, allowing the output end of a first LEU circuit to be connected withfour active transponders; when one of the first LEU circuit and a second LEU circuit fails, allowing the output end of the other normal LEU circuit to be connected with the active transponders; when both the first and second LEU circuits fail or remain normal, keeping existing connecting state of the first LEU circuit and the second LEU circuit unchanged. By the arrangement, frequent LEU switchingunder the situation that LEU1 channel is unstable is avoided, the situation that the transponders output default messages during switching is avoided, and normal operation of trains is guaranteed.