The invention discloses a supporting device for a hoisting system. The hoisting system comprises a top frame and a supporting device thereof, and is characterized in that the supporting device comprises a front support, a middle support and a rear support; the front support comprises a front support lower column body, a front support middle column body and a front support upper column body; the front support lower column body and the front support middle column body are fixed through a connection device; the front support middle column body and the front support upper column body are fixed through a connection device; the front support upper column body is provided with a fine adjustment mechanism; the rear support comprises a rear support lower column body and a rear support upper columnbody; the fine adjustment mechanism comprises a screw rod, nuts and an auxiliary hole; two nuts are arranged at the middle part of the screw rod; the auxiliary hole is formed in the middle part of thescrew rod; and internal threads cooperatively used with the screw rod are formed in the front support upper column body and/or the middle support upper column body and/or the rear support lower column body. The supporting device is high in assembling speed, and the supporting height can be adjusted, so that the applicability of the supporting device is improved.