The invention discloses a tool for quickly verifying a core of a secondary cable. The tool comprises a host terminal and a slave terminal. The host terminal comprises a main processor, a main alignment terminal block, an alignment generation module, a PLC industrial control board and a communication module. The slave terminal comprises a slave processor, a slave alignment terminal block and an alignment module. The main alignment terminal block is connected with each core wire of a multi-core cable on the host side, and the slave alignment terminal block is connected with each core wire of themulti-core cable on the slave side. The communication module is connected with the main processor and the slave processor. The PLC industrial control board is connected with the main alignment terminal block and the main processor. The alignment generation module is connected with the main processor. The alignment module is connected with the slave alignment terminal block and the slave processor. The slave processor sends an alignment signal to the alignment module, and the alignment module verifies the connection number of the slave side according to the number of the host-side core wire ofthe multi-core cable in the alignment signal. Full-automatic and rapid verification of the host side and the slave side of the cable core is realized.