Abstract: A non-invasive device for simultaneous testing dynamic characteristics and injection law of a gas needle valve and a method therefor are disclosed. The device includes a tested injector, a pressure sensor, a temperature sensor, an eddy current displacement sensor, a constant volume sealed container, and a controller. A nozzle of the tested injector is inserted into a constant volume cavity of the constant volume sealed container; the eddy current displacement sensor is arranged at a lower part of a gas needle valve of the tested injector; the pressure sensor and the temperature sensor are inserted into the constant volume cavity; and the controller is configured to receive displacement data, pressure data, and temperature data, and calculate the injection law of the tested injector based on the pressure data and the temperature data, achieving multi parameters testing of the needle valve lift and injection law in the same time and space.