The invention discloses a testing system device and a testing method for simulating water inrush through a deep tunnel fault in a complex condition. The device comprises a model testing chamber, a fault hazard-formation constructing system, a groundwater flow simulating system, a waterpower loading system, a top load controlling system, a data acquisition monitoring system, a water inrush mixture recycling system and a view recording system. The data acquisition monitoring system is pre-embedded inside the fault hazard-formation constructing system. The fault hazard-formation constructing system is arranged in the model testing chamber. The top load controlling system is arranged to load the top of the model testing chamber. The groundwater flow simulating system is communicated with the internal of the model testing chamber. The waterpower loading system is connected with the groundwater flow simulating system. The water inrush mixture recycling system is connected with a drain outlet of the model testing chamber. The view recording system records the whole water inrush hazard-formation testing process. The implementation method of the device can simulate water inrush through the tunnel fault under control of many factors such as different fault fracture zones, different water condition and different depths of tunnel.