The invention discloses a vehicle LNG gas cylinder multifunctional valve test system. The test system comprises a test tool, a multifunctional valve arranged on the test tool, a gas state test system for a gas state test of a corresponding valve port of the multifunctional valve, and a liquid state test system for a liquid state test of the valve port of the multifunctional valve, the gas state test system comprises a gas-inlet test pipeline and a gas-outlet test pipeline, the gas-inlet test pipeline is provided with a pressure-reducing valve, a safety valve, a plurality of stop valves, and a plurality of pressure gauges, the gas-inlet test pipeline is also communicated with a small gas cylinder via a small gas cylinder branch pipeline equipped with the stop valves, the gas-outlet test pipeline is provided with the pressure gauges and the stop valves, the liquid state test system comprises a liquid-inlet test pipeline and a liquid-outlet test pipeline, the liquid-inlet test pipeline is provided with the stop valves and the pressure gauges, and the liquid-outlet test pipeline is provided with the pressure gauges and the stop valves. According to the test system, various tests of different valves of the multifunctional valve can be conveniently accomplished.