The invention relates to an experimental device for the jet etching simulation and electrochemical test of a high-temperature high-pressure loop, which belongs to the field of electrochemistry and is particularly applied to the simulation of scouring corrosion conditions of complex parts such as elbows, T joints and the like in pipelines for collecting and delivering petroleum, natural gases and the like to perform high-temperature high-pressure multiphase fluid pipeline part scouring corrosion simulation experiments and perform high-temperature high-pressure fluid scouring corrosion in-situ electrochemical signal tests under scouring condition. The device consists of an autoclave, a heating and heat preservation system, a loop water inlet, a three-electrode system, pipeline connecting flanges, a circulation loop, a high-temperature high-pressure fluid flow meter, a control valve, a fluid outlet, a regenerating pump, a circulating cooling system, a temperature measurement system, a loop water outlet, a spray nozzle, a sample fixture, a control cabinet, a signal transduction path, an external electrochemical workstation and an external high pressure gas cylinder. The device can well simulate the scouring corrosion conditions of a fluid medium in a gas pipeline and test electrochemical signals such as polarization curves, AC impedance and the like of working electrodes under high speed jet condition, and is significant for researches on high-temperature high-pressure fluid scouring corrosion behaviors, rules and mechanisms.