Abstract: The objective of this study was to draw up the adjustment factor on 17 962 month milk yield records of Xinjiang Brown cattle. The lactation curve was fitted by five mathematical models (including the Wood′s incomplete gamma function model, inverse quadratic polynomial model, polynomial regression models (sextic), Ali-Schaeffer model and Wilmink model) with the nonlinear (NLIN) procedure, SAS(8.1) system. The results showed that the R2 values ranged from 0.834 0 to 0.921 4 for five models, depending on the model criteria, Inverse polynomial model was the best fitting model of lactation curves in this study, Lactation graph of different parities were drawn up, adjustment factors of milk production were drafted for Xinjiang Brown cattle. These results indicated that latest peak production occurred in first lactation for all models, while third lactation cows had the earliest day of peak production. With the growth of parity, milk production was increased continuously, while fifth parity cows had the highest milk production, and then gradually declined to agalorrhea, and means of 305-day milk yield was 4 445.3 kg.