A TFT and manufacturing method thereof, an array substrate and manufacturing method thereof, an X-ray detector and a display device are disclosed. The manufacturing method includes: forming a gate-insulating-layer thin film (3′), a semiconductor-layer thin film (4′) and a passivation-shielding-layer thin film (5′) successively; forming a pattern (5′) that includes a passivation shielding layer through one patterning process, so that a portion, sheltered by the passivation shielding layer, of the semiconductor-layer thin film forms a pattern of an active layer (4a′); and performing an ion doping process to a portion, not sheltered by the passivation shielding layer, of the semiconductor-layer thin film to form a pattern comprising a source electrode (4c′) and a drain electrode (4b′). The source electrode (4c′) and the drain electrode (4b′) are disposed on two sides of the active layer (4a′) respectively and in a same layer as the active layer (4a′). The manufacturing method can reduce the number of patterning processes and improve the performance of the thin film transistor in the array substrate.