The utility model relates to a supporting device for a low-voltage bus bridge of a transformer substation. The system comprises a station transformer and a power distribution room. A bus bridge is connected between the station transformer and the power distribution room. The supporting device further comprises a supporting column located between the station transformer and the power distribution room. A section of supporting frame A is installed at the top of the supporting column, a section of supporting frame B is installed at the top of the station transformer, the supporting frame B is higher than a radiator arranged on the station transformer, the supporting frame A and the supporting frame B are fixedly connected through a connecting piece, and supporting column porcelain bottles used for supporting a bus bridge are installed at the top of the supporting frame A and the top of the supporting frame B respectively. The utility model avoids the problem that the stable operation of the radiator is influenced by vibration when the bus bridge works.