The utility model discloses a B sign indicating number timing device, including the GPS clock synchronization system, time synchronization system set up a GPS to the time master clock and a plurality of GPS to the time assist the clock, GPS to the time master clock install in the relay protection main chamber, through the B sign indicating number to the time optic fibre be connected to a plurality of GPS to the time assist the clock to through the B sign indicating number to the time net twine be connected to the multiple protection device of relay protection main chamber, GPS to the time assist the clock and install and assist the room at relay protection, and through the B sign indicating number to the time net twine be connected to the multiple protection device that relay protection assisted the room. The utility model discloses a behind the GPS time synchronization system, can improve to the time the accuracy, ensure the protection device true( -)running at full station, to the time safer, avoid to the time rely on and always to control the unit, to the time more independent, the equipment cable is more simplified, it is convenient to maintain, maintains cost reduction.