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The D_α signal photoelectric detection system with high temporal and spatial resolution consists of 16 channels, each channel consists of a photomultiplier tube (PMT) and a current amplifier based on a sapphire material instead of a conventional printed circuit board. In order to enable the detection of the fast-ion D_α (FIDA) signal from other light sources of the same spectral range when a neutral beam is injected, the system parameters were designed with a total photon-to-voltage gain of 5.0×10⁹, the current amplifier with a current-to-voltage gain of 106V/A and a −3dB bandwidth at 500kHz. The EAST discharge experiment showed that the FIDA signal was well detected by this photoelectric detection system and the fast-ion properties were deduced from the Doppler shift spectrum of the D_α light.