The invention provides an electrolytic bath apparatus used for simulating a deep-sea environment for electrochemical testing, belonging to the field of corrosion testing of metal materials. The electrolytic bath apparatus comprises an electrolytic bath main body which is prepared from at least three layers of different metal materials, i.e., an inner corrosion-resistant layer, an outer pressure-resistant layer and an electromagnetic wave shielding layer arranged between the inner corrosion-resistant layer and the outer pressure-resistant layer; three electrode subassembly installing holes, two air vents and one hydraulic pressurization hole are preset in the top cover of an electrolytic bath; and the hydraulic pressurization hole is connected with hydraulic pressurization equipment via a connection flexible pipe. The apparatus provided by the invention is based on the electrolytic bath main body for electrochemical measurement, can realize simulation of the deep-sea environment at the same time, and has the advantages of simple operation, low time consumption, economic performance, a large pressure control scope, fast pressurization speed, accurate temperature control, firm and durable structure, etc. Testing data acquired by using the electrolytic bath apparatus can truly reflect the corrosion-electrochemical performance of a metal material in a simulated deep-sea environment, and the electrolytic bath apparatus provides a more favorable corrosion measurement means for research on materials used in deep-sea environments.