Abstract: 【Objective】 To study the growth and development of body size traits such as body weight, body height, and body length in Kazakh sheep, Simplify part of the workload and provide a reference for Kazakh sheep breeding. 【Methods】 In the experiment, a total of 1091 Kazakh ewes over 12 months of age, including body weight and 8 individual ruler traits were collected, and statistical analysis of each trait was conducted. 【Results】 The coefficient of variation of body size traits of Kazakh sheep was at the normal level, and the coefficient of variation of tail width and tail length was the largest, reaching 17.42% and 16.9% respectively. Body weight was significantly correlated with body length and chest circumference (P<0.01), and negatively correlated with tail width and tail length (P<0.01). 3 representative principal components were extracted from 9 principal components, which reflected body weight, body length, body width, girth and body height of Kazakh sheep respectively. We found that fitting the regression equation with the principal component extraction factor was more accurate than directly using body size traits. 【Conclusion】 Principal component extraction factor can better analyze the internal relationship between body weight and traits of Kazakh sheep.