The invention provides a weighing data processing method of a siamesed balance with double tables, wherein double tables use respectively independent weighing data filter parameters and respectively and independently judge the high and low levels of the number of axles, by aiming at the phenomenon that the number of axles measured by a highway dynamic weighing system is inaccurate, specially the phenomenon that the axles are easily reduced when connecting axles are measured. The low level is adopted to fix, and the high level can be automatically regulated according to the weight, so that the probability that the number of large axles is not accurate when the level is too low or the number of small axles is not accurate when the level is too large. The weight, speed, accelerated speed and number of axles of the measuring data of the two tables are judged, so as to select or calculate more accurate weighing results, and improve the accuracy rate of the measurement of the number of axles of the siamesed balance and the precision of the measurement of a finished automobile.