The invention relates to a method for manufacturing a photodiode. The method includes the following steps: providing a semiconductor substrate and forming a photodiode PN junction in the semiconductor substrate, the photodiode PN junction and an active device in an analog circuit being formed synchronously; depositing to form a multi-layer structure on the semiconductor substrate; forming a window in the multi-layer structure, the window being arranged on the PN junction of the photodiode; and depositing silicon nitride and/or silicon dioxide on the window area surface to form a reflecting layer. In addition, also provided are a photodiode and an optical inductor. Under the circumstance that original device performance is kept unchanged in an existing semiconductor technology, the photodiode PN junction and the active device in the analog circuit are synchronously formed, the corrosion technology of the photodiode window is changed at the same time, the window area is additionally provided with the reflecting layer, and single-chip integration of the photodiode and the active device in the analog circuit on an arbitrary technology platform is realized. The technological process of integration of the photodiode and the analog circuit in the same chip is simple and is low in cost.