Abstract: Aiming at estimating weight of pig with image processing technology， felicitous estimating model is the base and key to achieve good results also connected directly to the complexity，stability and high efficiency of processing Algorithms. Analysised the factors correlated to weight estimating and characteristics of bodily form of pig，divided the pig into head and body and supposed them as a cone and a columniation. Set up an estimate model based on three-dimension. The results of comparisonand analysising betweenactual and estimating weight values verified the estimating model through experiment and got a pretty precision in the range of experiment weight datas.This study provided a new method to estimate pigs′ weight non-destructively.