The invention discloses an adjustable mounting bracket for a light aero-engine. The adjustable mounting bracket for the light aero-engine comprises a supporting frame, a rotating assembly and a clamping assembly. Two first supporting columns and two second supporting columns are fixedly connected to the upper surface of the supporting frame, a first supporting plate is fixedly mounted on the uppersurfaces of the two first supporting columns, a first bearing seat is fixedly mounted on the upper surface of the first supporting plate. A second supporting plate is fixedly mounted the upper surfaces of the two second supporting columns, and a second bearing seat is fixedly mounted on the upper surface of the second supporting plate. A gear is matched with the upper end of a first connecting rod, in cooperation with the use of a gravity block, and the gear and the upper end of the first connecting rod abut against each other, so that the rotation of the rotating assembly is restrained; by stepping on a pedal and rotating a rotary hand wheel, the angle of the light aero-engine is adjusted for installation; and the mounting bracket has simple structure, ingenious design, convenient operation, flexible use, low cost and high promotion value.