The invention discloses a liquid metal sodium boiling two-phase thermal-hydraulic test loop system and a test method thereof. The loop system is divided into three parts comprising a high temperature part, a low temperature part and an argon branch, wherein the low temperature part comprises a sodium storage tank, an electromagnetic pump, an electromagnetic flowmeter, a purification cold trap, four sodium valves and corresponding connecting pipelines; the low temperature part is made of 316L stainless steel; the high temperature part comprises a regeneration heater, a preheater, a test section, an upper expansion box and corresponding connecting pipelines; the high temperature part is made of Incoloy 800 and allows the operating temperature to reach 1,200 DEG C; and the argon branch comprises an argon bottle, an expansion pressure stabilizing box, a vacuum pump, three pressure gauges, ten vacuum diaphragm valves and corresponding connecting pipelines. The system is suitable for operating at high temperature, has a good sealing property and can realize analysis and research on the liquid metal sodium boiling two-phase heat exchange flow characteristic by adding different test sections and a data acquisition system.