The utility model discloses a circuit to improve the performance of a 1553B bus. The circuit includes a switching coupler and a coupler with a terminating resistor. An output end of the switching coupler is connected with an input end of the coupler with the terminating resistor. An internal circuit of the switching coupler is provided with a relay for switching and a terminating resistor, a normally closed contact of the relay is connected with the terminating resistor, a normally open contact of the relay is connected with a 1553B main bus, and a switch is connected with the coupler in series. The coupler with the terminating resistor includes a coupler and a terminating resistor, one end of the coupler is connected with the terminating resistor, and the other end of the coupler is connected with the main bus 1553B. According to the utility model, the terminal mating resistor is integrated in the coupler, an independent redundant dual relay is disposed in the switching coupler, reliable disconnection of signals is ensured, and the independence and reliability of internal control of the coupler are achieved through the design of the internal circuit of the coupler.