Abstract: To investigate the correlation of body weight, body size and the characteristics of breast growth and development of lactating Bactrian camels in Junggar, Xinjiang, the weight, body size trait indexes（body length, body height, chest circumference, tube circumference） and papillary traits indexes（nipple length, nipple diameter） of 247 peak 4-15 year old Junggar lactating Bactrian camels from Altay Region of Xinjiang were measured. Then R language software was used to analyze the correlation between body weight and each body size trait index, and SPSS 26.0 software was used to analyze the path of each body size trait index to body weight. The regression equation of weight prediction was established by stepwise regression analysis. Finally, the regression equation for weight prediction was verified by randomly selecting 2 humping camels in each age group from 50 humping Bactrian camels aged 4 to 15 years in the grazing area of Jimunai County, Altai Prefecture. The results showed that the average body weight, average body height, average body length, average chest circumference, average chest circumference and average tube circumference were 522.30 kg, 169.07 cm, 148.80 cm, 218.69 cm and 19.18 cm respectively. The coefficient of variation of body height is the smallest, followed by body length and chest circumference, and the coefficient of variation of body weight is the largest.The average length of the right anterior, right posterior, left anterior and left posterior nipple was 3.15, 2.96, 3.03, 3.02 cm, respectirely. The range of nipple length was 2.08 cm. The average diameter of the right anterior, right posterior, left anterior, left posterior nipple was 2.91, 2.88, 2.91, 2.88 cm, respectirely, and the diameter range of the nipple was 1.78 cm. The data of body weight and body size traits were normally distributed. Body weight was positively correlated with body height, body length, chest circumference and tube circumference（P＜0.001）, among which the correlation with chest circumference was the highest（0.74）, followed by body length（0.61）, body height（0.58） and tube circumference（0.56）.Chest circumference had the greatest direct effect on body weight（0.498）, followed by body length（0.406） and body height（0.369） in that order, and tube circumference had the least direct effect on body weight（0.358）. The indirect effect of body height on body weight was the largest（0.271）, then chest circumference（0.268） and body length（0.263） in that order, and tube circumference had the smallest indirect effect on body weight（0.254）. The correlation coefficient between chest circumference and body weight was the largest（0.640）. The regression equation for predicted body weight was constructed by stepwise regression analysis as Y=-1.085.980+2.450X₁+3.075X₂+2.822X₃+6.923X₄（Y、X₁、X₂、X₃、X₄ standed for weight, body height, body length, chest circumference and tube circumference, respectively）, and the root-mean-square error between the measured body weight values and the predicted body weight values of the model was 0.51, with a well-fitting curve; the Pearson′s correlation coefficient was 0.882, which was a highly significant correlation（P＜0.01）. There was no significant difference in the confidence interval of significant level α=0.05（P＞0.05）. The results indicated that the body weight changed greatly and the body size changed slightly during the growth and development of lactating Bactrian camel population in Junggar, Xinjiang. The nipple length and diameter of different individuals varied greatly, and the length of anterior nipple was generally longer than that of posterior nipple. Among all body size traits, chest circumference had the greatest influence on body weight. The weight prediction regression equation established could accurately predict the body weight of lactating bactrian camels in Juggar.