A detection substrate and a ray detector are disclosed. The detection substrate includes a base substrate; a plurality of detection pixel circuits, located on the base substrate; a first passivation layer, located on the side, facing away from the base substrate, of the detection pixel circuits; a planarization layer, located on the side, facing away from the base substrate, of the first passivation layer, where the surface of the side, facing away from the first passivation layer, of the planarization layer is a plane; and a plurality of photosensitive devices; where the photosensitive devices are electrically connected to the detection pixel circuits in a one-to-one correspondence through vias penetrating through the first passivation layer and the planarization layer, and each photosensitive device includes a first portion and a second portion.