Abstract: The field dynamic balancing of the antenna prototype of an X-band airport surface surveillance radar is tested and analyzed in this paper. The unbalance position and unbalance value are measured by the field dynamic balancing, and then the corresponding mass is added to the symmetrical direction to match the unbalance. The vibration and vibration force caused by the unbalance are reduced to the allowable range. Tests show that the field dynamic balancing is easy to operate, the test cost is reduced, and the error caused by the second assembly can be avoided. The field dynamic balancing test and analysis indicate that the dynamic balancing performance of the antenna rotor meets the accuracy requirements. It shows that the prototype can handle the mass eccentricity well in the design and machining process, and a better performance of dynamic balancing is obtained with the counterweight added. As a mature and practical technology, this field dynamic balancing test technology for large rotors has brought considerable economic benefits to enterprises.