The invention provides a gas well fracturing flow-back fluid separation device, which includes a gas-liquid separation tank. The upper air outlet of the gas-liquid separation tank is provided with an upward floating ball valve, the lower liquid outlet is provided with a downward floating ball valve, and a baffling separation plate is disposed between the upward floating ball valve and the downward floating ball valve. One side inlet of the gas-liquid separation tank is connected to a flow-back fluid inlet through a pipeline. The pipeline between the gas-liquid separation tank and the flow-back fluid inlet is also connected to an energy dissipater, the upper air outlet of the gas-liquid separation tank is in connection with a gas collector through a pipeline, the gas-liquid separation tank lower liquid outlet is connected to a liquid-solid separator through a pipeline. The fracturing flow-back fluid separation technology and device provided by the invention adopt vertical separation, and the formed liquid level is high, thus being convenient to control the liquid outlet. The air outlet and liquid outlet adopt floating ball valve control, thus realizing only liquid can be discharged through the liquid outlet and only gas can be discharged throught the air outlet when the gas-liquid ratio is very large or small.