The invention discloses an adjusting mechanism for a stroller backrest with a single hand. The adjusting mechanism comprises a backrest part, a first adjusting band, a reversing buckle, a second adjusting band, a fastener and a tension band. The bottom of the backrest part is used for being hinged onto a stroller body of the stroller. One end of the first adjusting band is connected with the stroller body of the stroller. The reversing buckle is provided with an inlet allowing the first adjusting band to penetrate in and an outlet allowing the first adjusting band to penetrate out. The inlet and the outlet are intersected in terms of direction. The second adjusting band is connected with the other end of the first adjusting band penetrating out of the outlet. The fastener is arranged at the top of the backrest part. The second adjusting band is provided with a penetrating portion, out of which the fastener penetrates. One end of the tension band is connected with the reversing buckle and the other end of the tension band is used for being connected with the strollerbody. The adjusting mechanism for the stroller backrest with the signal hand facilitates adjusting degrees of the backrest or expanding/folding the backrest with the single hand and is low in cost.