The disclosure provides a light detection substrate, a manufacturing method thereof and a light detection apparatus. The light detection substrate includes a plurality of light detection units, each of the light detection units includes a first electrode, a second electrode and a photoelectric conversion layer, a spacer region exists between orthographic projections of the first electrode and the second electrode on a substrate, the photoelectric conversion layer is provided with at least one opening, and an orthographic projection of the at least one opening on the substrate is located in the spacer region.