In this paper,the authors carried out continuous measurements on the growth performance of three leantype breeds,Duroc,Landrace and Yorkshire (30~50 kg and 30~100 kg),and explored the optimal fitting model to study the early development.The regression analysis in variety conditions,between the early age and weight,weight and back fat,with nonlinear model and linear models,such as Logistic,Gompertz,Saturation,Quadratic and Polynomial etc,were analyzed based on the testing data of 678 pigs in five typical pig farms of Hubei Province.The results showed that,the three modles (Logistic,Gompertz,and Saturation) in a certain range are all suitable for researching on the growth development on age and weight of lean pigs.In meaning of the biological sense,Gompertz model is better than the Logistic model.While the Saturation model can get a good and simple fit.And this model didn’t change transformation of metatype,with the advantages of developing revision formula.Logistic and the Gompertz model is not suitable for study on weight and backfat development law,while Saturation model has good biological sense in the development law of weight and back fat,and within the limits of the growth phase of any weight,has continuous point forecast function about the back fat.So,the Satuartion model is the most suitable fitting model.