An electric guide rail type conveying system comprises a driving motor, a guide rail, a main transmission case, an auxiliary transmission case, a conveying member, and a moving trolley. Both ends of the conveying member are elastically deformably wound on the first rotating member and the second rotating member of a main transmission case body in two opposite winding direction. Before installation, the conveying member is basically wound on the first rotating member and the second rotating member. When a relative outer portion of the conveying member wound on the first rotating member is separated from the rotating member, a first elastic resilience opposite to one of the two opposite winding direction is generated; with the increase of a portion, separated from the first rotating member, of the conveying member, the first elastic resilience will increase; otherwise, the first elastic resilience will decrease.