The invention provides a high-precision measurement device for mass center of a large-mass-deviation workpiece. Two linear guiderails support two floating boards. The upper surface of each floating board is provided with two linear guiderails in a left-and-right direction for supporting two roller brackets. Each roller bracket is provided with a clamping structure. Four corners of the lower surface of a table are provided with four first supporting points which are fixedly connected with the table. Three elongated supporting strips are distributed along the central point of the lower surface of the table in an axis symmetry manner. A plurality of uniformly distributed second supporting points are mounted in the long side direction of the elongated supporting strip below the elongated supporting strips. Four corners of the upper surface of a table seat are provided with four lifters which are respectively driven by two speed reducers coaxially. The two speed reducers are coaxially driven by a motor. Four corners of the upper surface of the table seat are provided with four first sensor seats. The upper part of the first sensor seat is fixedly connected with a high load sensor. The upper surface of the table seat is provided with three second sensor seats which are right below the supporting strips and are driven by a motor ball screw. The upper part of the second sensor seat is fixedly connected with a low load sensor.