The invention provides a system used for detecting charge and electric field response of a semiconductor device. The system comprises a current loop and a pulse laser. A semiconductor device to be detected is connected in the current loop. The pulse laser is used for applying a laser pulse on a semiconductor device to be detected periodically and thus photo-generated charges are generated in the semiconductor device. The photo-generated charges are transmitted in the current loop to form a transient photo-generated current. a sampling resistor arranged in the current loop and in series connection with the semiconductor device, a voltage signal collector in parallel connection with the sampling resistor and used for collecting voltage difference signals of two ends of the sampling resistor, a voltage source in parallel connection with the semiconductor device and used for providing a modulation voltage which changes periodically for the semiconductor device, a current isolator in series connection with the voltage source and used for preventing the transient photo-generated current or the high-frequency part from passing the voltage source. The system can detect a transient photo-generated current accurately and is suitable for detection of a slow charge response process in a semiconductor device.