The present invention relates to a belt weigher error decomposition control method and a belt weigher system composition. The key points of a corresponding technical scheme are that by adding the parts of special structures in the basic composition of a general belt weigher or adopting the special measures, an overall error is decomposed into several independent basic error terms, and different compensation and correction methods are respectively carried out on an error caused by the construction of a load receptor, a measurement circuit and the like and an error caused by a belt effect, thereby controlling the parameters of the basic error terms, and remarkably improving the performances of the belt weigher, such as the accuracy, the repeatability, the stability, the durability, etc. The belt weigher error decomposition control method and the belt weigher system composition are especially suitable for the occasions having high metering data requirements, such as the trade settlement, etc. The reliability and the credibility of a calibration result obtained by using the simulation loads to substitute for the objects are much better than the prior art, so that the belt weigher error decomposition control method and the belt weigher system composition have the very high economic and practical values.