The invention discloses a multipoint ground-connection current control method for three current transformers to monitor lower transformer clamping parts. The multipoint ground-connection current control method solves the problem that a power-cut current limiting operation method for ground-connection current of the transformer clamping parts in the prior art can affect normal operation of a power grid. A clamping part ground-connection outgoing line (9) penetrates through a coil of the first current transformer (10) to be connected with the input end (21) of a switching circuit, the two ends of the secondary side induction coils of the three current transformers are respectively connected with two input ports of an AD conversion port circuit, the output end of the AD conversion port circuit (15) is connected with a single chip microcomputer (17), the output end (22) of the switching circuit is connected with the ground-connection end (6), impedance units, used for limiting current impedance units, of three switching branches use bidirectional thyristors to control the branches to be turned on and off, and an impedance branch can be controlled to be turned on and off by controlling a conduction angle to achieve the purpose of switching the impedance units. The multipoint ground-connection current control method is high in operability and guarantees normal safety operation of the power grid.