A method for fabricating a sensor, comprises: forming, on a base substrate, a pattern of a data line (31), a pattern of a drain electrode (34), a pattern of a source electrode (33), a pattern of a receive electrode (39), a pattern of a photodiode (40) and a pattern of a transparent electrode (41); forming a pattern of an ohmic layer by using a first patterning process; forming a pattern of an active layer by using a second patterning process; forming a pattern of a gate insulating layer by using a third patterning process; and forming a pattern of a gate line (30), a pattern of a gate electrode (38) and a pattern of a bias electrode (42) by using a fourth patterning process. Such a method can reduce the number of mask as well as the production cost and simplifies the production process, thereby significantly improves the production capacity and the defect-free rate.