A thin film transistor and a producing method thereof, and an array substrate, which belong to a technical field of the thin film transistor, can solve a problem of poor performance of a conventional thin film transistor. The producing method of the thin film transistor comprises: S1: forming a gate electrode (11) composed of graphene; S2: forming a gate insulating layer (12) composed of oxidized graphene; S3: forming an active region (13) composed of doped oxidized graphene or doped graphene; S4: forming a source electrode (14) and a drain electrode (15) composed of graphene, wherein, the graphene composing the source electrode (14), the drain electrode (15) and the gate electrode (11) is formed by reducing oxidized graphene, and the doped oxidized graphene or doped graphene composing the active region (13) is formed by treating oxidized graphene.