A detecting system for fire is provided. The detecting system includes a sensing device, a control center, and a physical circuit. The sensing device is disposed in a sensing area. The sensing device is for obtaining target information, environmental information, and location information, and for outputting sensing information. The sensing area includes a sub-sensing area corresponding to the sensing device. The control center is coupled to the sensing device. The control center is for outputting integrated information based on sensing information. The physical circuit is for coupling the sensing device and the control center. The sensing device obtains the unique location information corresponding to the sub-sensing area according to the physical circuit.