Abstract: As classical photodetection approaches its performance limits, quantum-optics-based photodetection has drawn growing interest for its demonstrated advantages in mitigating environmental noise, sensing weak targets at long range, and achieving ultimate sensitivity. In this paper, a review was conducted on the current state and distinctive features of representative quantum-optic imaging and detection techniques. Future research directions were discussed, and perspectives on further development were offered from the viewpoints of underlying physics, device engineering, and signal processing.