The invention belongs to the field of internal combustion engine researches and discloses a natural gas / diesel oil dual fuel injection mixed characteristic research device and a control method thereof. The device comprises an injection combiner, a constant volume bomb, a natural gas injector, a diesel oil injector, a gas supply system, an oil supply system, a computer I, an ECU, a laser, a synchronizer, a camera I, a camera II, a reflector and a spectroscope. The natural gas injector and the diesel oil injector are fixedly installed in the injection combiner. The injection combiner is installed at the top of the constant volume bomb. The gas supply system is connected with the natural gas injector. The oil supply system is connected with the diesel oil injector. The ECU controls the natural gas injector and the diesel oil injector to be started or stopped. The computer I controls the laser, the camera I and the camera II to work synchronously through the synchronizer. According to the natural gas / diesel oil dual fuel injection mixed characteristic research device and the control method thereof, dual fuel injection mixing is achieved, clear mist form images are captured through a laser induced fluorescence technique, and a heating unit, a temperature and pressure sensor and an electromagnetic flowmeter are arranged in a pipeline so as to research the influence of the state of fuel on the mist mixed characteristics.