A novel hybrid integrated photodetector with flat-top steep-edge spectral response, which consists of a Si-based multi-cavity Fabry-Pérot (F-P) filter and an InP-based cone absorption cavity (with a 0.2 m In0.53Ga0.47As absorption layer), has been designed and fabricated. The operating lightwave is well confined to the cone absorption, and experiences multiple reflections across the absorption layer. Thus, an absorption enhancement effect without resonance can be achieved. Based on multi-cavity F-P structure and a cone cavity, this device can get good flat-top steep-edge spectral response and high quantum efficiency. The photodetector is fabricated by bonding a Si-based multi-cavity F-P filter with an InP-based cone absorption cavity. An integrated device with a peak quantum efficiency of 60% around 1550 nm, the dB band of 0.5 nm, and the 25 dB band of 1.06 nm, is simultaneously obtained.