The present invention may provide an AI system for inferring the weight of livestock, comprising: a data collection unit for collecting, as one data set, 3D data and a 2D image acquired by capturing one or more livestock animals, wherein one or more data sets are collected; a weight inference unit for predicting the weight of a target livestock animal from the data set(s), and proposing a similarity function value and a recommended weight value on the basis of a knowledge database; and a comprehensive weight prediction model for deriving a final weight prediction value by receiving a weight prediction result value based on the data set(s) and predicted by the weight inference unit.