A radiographic detection substrate, a manufacture method thereof, and a radiographic detection device are provided. The radiographic detection substrate includes a substrate; and a thin film transistor and a signal storage unit which are formed on the substrate; the thin film transistor includes a gate electrode, an insulating layer, an active layer, a source electrode, a drain electrode and a passivation layer which are sequentially formed on the substrate; the signal storage unit includes a storage capacitor, the storage capacitor includes a first electrode and a second electrode, the first electrode is formed on the insulating layer and lapped with the drain electrode, the second electrode is connected to a ground line; the passivation layer is formed on the source electrode, the drain electrode, the first electrode and the ground line. The present invention efficiently decreases the number of masking processes by at least one connection method selected from lapping the first electrode and the drain electrode, connecting the second electrode to the ground line through the first via hole, and connecting the third electrode to the first electrode via the second via hole, to simplify the manufacture process of the radiographic detection substrate and reduce the manufacture costs.