The invention relates to a leveling barge and discloses a platform type riprap leveling barge and a construction method thereof. The leveling barge comprises a barge body, a first global position system (GPS), an operation room, a moon pool, a leveling guide mechanism, a riprap leveling device, and a stone conveying mechanism, wherein the first GPS and the operation room are respectively arranged on the barge body, the moon pool is arranged at the center of the barge body, the leveling guide mechanism stretches across the moon pool, and the riprap leveling device is installed on the leveling guide mechanism. According to the platform type riprap leveling barge and the construction method thereof, the barge body is stable, construction efficiency is high, safety is high, and bed flatness after construction is high; by means of four pile legs, the leveling barge is lifted to leave a sea surface or a river surface and perform overload ballast, so that stability of the barge body of the leveling barge during construction is guaranteed, and the influence of natural conditions such as waves, flows, and wind on the barge body are small during a riprap leveling process; a second GPS at the top of a riprap pipe receives three-dimensional coordinate data and controls an elevation of a rubble bed in combination with the length of the riprap pipe, an inclined angle of the riprap pipe, and the stroke of a bottom hydraulic cylinder, and the measurement accuracy control is accurate.