The invention discloses a vehicle-mounted weighing method and relates to the field of vehicle-mounted weighing. The vehicle-mounted weighing method comprises the following steps: firstly, sending a vehicle-mounted weighting request instruction by a first node and receiving the vehicle-mounted weighting request instruction by a vehicle-mounted communication node; secondly, collecting the vehicle-mounted data by a weighting sensor at intervals and judging if the loading state is under balanced state by a first processing unit; if the loading state is under balanced state, performing the first operation on the loading data, thereby acquiring a loading equivalent average value; if the loading state is under non-balanced state, performing the second operation on the loading data, thereby acquiring the loading equivalent average value; lastly, sending a vehicle-mounted weighting equivalent average value by the vehicle-mounted communication node and receiving the vehicle-mounted weighting data by the second node. According to the vehicle-mounted weighing method, the vehicle-mounted weighting halt-free measurement is realized and the check time for vehicle overload is saved. Meanwhile, the vehicle-mounted weighting information is acquired by performing different operations according to the loading state under balanced state or non-balanced state, namely, the fluctuation index of vehicle-mounted data. The measuring accuracy of the vehicle-mounted weighting is increased.