The invention discloses an array substrate of an X-ray detection device and a manufacturing method thereof. The array substrate comprises a thin film transistor device and a photoelectric diode sensor connected with the thin film transistor device, wherein the thin film transistor device comprises a source electrode, a drain electrode, an ohm layer, an active layer, a grid electrode insulating layer and a grid electrode, wherein the source electrode and the drain electrode are formed on a substrate base plate; the ohm layer is formed above the source electrode and the drain electrode; the active layer is formed above the ohm layer and forms a channel with the source electrode and the drain electrode; the grid electrode insulating layer is formed above the active layer and covers the whole base plate; and the grid electrode forms above the grid electrode insulating layer and is positioned above the active layer. The array substrate and the manufacturing method thereof have the beneficial effects that as the thin film transistor device is of a top grid type structure, the channel can be protected while a photoelectric diode and a transparent electrode are etched, so that the mask process forming process of a channel blocking layer is omitted, the manufacturing process of the array substrate is simplified, and the productivity is improved; through the top grid type grid electrode, light rays are effectively blocked, so that the current leaked from the channel is greatly reduced; and a light shade is not required to be additionally arranged, so that the production cost is further reduced.