The invention discloses a device for treating industrial mercury-containing wastewater containing high-concentration chlorides and a control method. The device comprises a heavy metal online automatic analyzer, a PLC (Programmable Logic Controller) process intelligent feedback control system, a mercaptan composite inorganic ceramic filtering tower, a medicine storage pot, a buffer pool, a filter, a pH automatic modulation control system, an adsorption tower and an ion exchange tower; the heavy metal online automatic analyzer is arranged at an end opening of a water inlet pipe; one end of the heavy metal online automatic analyzer is connected with the mercaptan composite inorganic ceramic filtering tower through a pipeline; the mercaptan composite inorganic ceramic filtering tower is connected with the buffer pool through a pipeline; the medicine storage pot is arranged between the mercaptan composite inorganic ceramic filtering tower and the buffer pool; the buffer pool is connected with the filter through a pipeline; the filter is connected with the adsorption tower a the pipeline; the adsorption tower is connected with the ion exchange tower through a pipeline. According to the device and the control method disclosed by the invention, the intelligentization of the system is realized; meanwhile, the quality of water discharged from the system is improved, the treatment cost is reduced, a good mercury removing effect is realized, and no secondary pollution is caused.