A loop-adjustable exhaust gas recirculation system comprises a diesel engine (10), a gas compressor (20), a turbine (30), a high-pressure regulating pipeline (40), a low-pressure regulating pipeline (50) and a high-low pressure communicating pipeline (60). The high-pressure regulating pipeline comprises a high-pressure intercooler (42) and a high-pressure control valve (44), and the low-pressure regulating pipeline comprises a low-pressure intercooler (52) and a low-pressure control valve (54). One end of the high-low pressure communicating pipeline is connected to the communication position of the high-pressure intercooler and the high-pressure control valve, while the other end of the same is connected to an outlet of the low-pressure control valve of the low-pressure regulating pipeline, and the high-low pressure communicating pipeline comprises a high-low pressure regulating valve (64). Under different operating conditions of the diesel engine, opening of the high-pressure control valve, the low-pressure control valve and the high-low pressure control valve is controlled, exhaust gas recirculation in different loop forms can be realized, adaptation of the exhaust gas recirculation system within a total operation condition range is improved, and diesel engine performance is improved.